Pointers are commonly used with arrays in C to iterate through elements and access data. Pointers store the memory address of the variable they are pointing to. To access the value of the pointer, the dereference operator * is used. Pointer arithmetic allows pointers to be incremented or decremented to access successive elements in an array. Functions can accept pointers to arrays rather than the entire array. Multidimensional arrays can be implemented by having arrays of pointers in C.
A pointer is a variable that stores the memory address of another variable. Pointers allow functions to modify variables in the caller and are useful for handling arrays and dynamic memory allocation. Pointers contain the address of the memory location they point to. Pointer variables can be declared to hold these memory addresses and can then be used to indirectly access the value at the addressed location.
This document provides an overview of pointers in C programming. It defines pointers as variables that store memory addresses rather than values. Pointers have several useful applications like accessing variables outside functions, passing information between functions, and more efficiently handling data tables. The document explains how to declare pointer variables, assign the address of a variable to a pointer, dereference a pointer to access the value at an address, and pass pointers to functions. It also discusses pointers and arrays, structures, and arrays of structures.
Hamid Milton Mansaray teaches the chapter on arrays, pointers, and strings in week 8. Some key points covered include initializing and accessing elements of one-dimensional arrays using indexing or pointers, passing arrays to functions by reference using pointers, pointer arithmetic and comparing pointers, dynamic memory allocation for arrays using calloc and malloc, and how strings are implemented as character arrays in C with a null terminator. Examples are provided for summing arrays, merging sorted arrays, and basic pointer operations.
A pointer is a variable that stores the memory address of another variable. Pointers allow accessing and modifying the data stored at the referenced memory location. Pointers can be declared by specifying the data type followed by an asterisk, and are initialized by assigning the address of a variable to the pointer variable. Pointer variables can be used in expressions and arithmetic and can be passed to functions to modify the referenced data. Arrays can also be accessed and traversed using pointers by treating the array name as a pointer to its first element. Pointers to functions allow functions to be passed as arguments and enables polymorphism.
- A pointer is a variable that stores the address of another variable. Pointers allow dynamic memory allocation and access to the value of the variable being pointed to using the indirection operator (*).
- Pointer variables are declared with a data type followed by an asterisk, such as int *ptr. They can be initialized by using the address-of operator (&) to store the address of another variable.
- Pointers can be used to access elements in an array by using pointer arithmetic. An array name itself is a constant pointer to the first element of the array.
Homework Assignment – Array Technical DocumentWrite a technical .pdfaroraopticals15
Homework Assignment – Array Technical Document
Write a technical document that describes the structure and use of arrays. The document should
be 3 to 5 pages and include an Introduction section, giving a brief synopsis of the document and
arrays, a Body section, describing arrays and giving an annotated example of their use as a
programming construct, and a conclusion to revisit important information about arrays described
in the Body of the document. Some suggested material to include:
Declaring arrays of various types
Array pointers
Printing and processing arrays
Sorting and searching arrays
Multidimensional arrays
Indexing arrays of various dimension
Array representation in memory by data type
Passing arrays as arguments
If you find any useful images on the Internet, you can use them as long as you cite the source in
end notes.
Solution
Array is a collection of variables of the same type that are referenced by a common name.
Specific elements or variables in the array are accessed by means of index into the array.
If taking about C, In C all arrays consist of contiguous memory locations. The lowest address
corresponds to the first element in the array while the largest address corresponds to the last
element in the array.
C supports both single and multi-dimensional arrays.
1) Single Dimension Arrays:-
Syntax:- type var_name[size];
where type is the type of each element in the array, var_name is any valid identifier, and size is
the number of elements in the array which has to be a constant value.
*Array always use zero as index to first element.
The valid indices for array above are 0 .. 4, i.e. 0 .. number of elements - 1
For Example :- To load an array with values 0 .. 99
int x[100] ;
int i ;
for ( i = 0; i < 100; i++ )
x[i] = i ;
To determine to size of an array at run time the sizeof operator is used. This returns the size in
bytes of its argument. The name of the array is given as the operand
size_of_array = sizeof ( array_name ) ;
2) Initialisg array:-
Arrays can be initialised at time of declaration in the following manner.
type array[ size ] = { value list };
For Example :-
int i[5] = {1, 2, 3, 4, 5 } ;
i[0] = 1, i[1] = 2, etc.
The size specification in the declaration may be omitted which causes the compiler to count the
number of elements in the value list and allocate appropriate storage.
For Example :- int i[ ] = { 1, 2, 3, 4, 5 } ;
3) Multidimensional array:-
Multidimensional arrays of any dimension are possible in C but in practice only two or three
dimensional arrays are workable. The most common multidimensional array is a two
dimensional array for example the computer display, board games, a mathematical matrix etc.
Syntax :type name [ rows ] [ columns ] ;
For Example :- 2D array of dimension 2 X 3.
int d[ 2 ] [ 3 ] ;
A two dimensional array is actually an array of arrays, in the above case an array of two integer
arrays (the rows) each with three elements, and is stored row-wise in memory.
For Example :- Program to fill .
The document discusses pointers in C programming. It defines pointers as variables that contain memory addresses and can point to different data types. It covers pointer arithmetic, passing pointers to functions, and using pointers with arrays, including arrays of pointers. Functions can be called by value by passing the variable itself, or by reference by passing the memory address of the variable using pointers, allowing the function to modify the original variable. Pointer notation can be used to access elements of two-dimensional arrays.
The document discusses pointers and arrays in C programming. It explains that an array stores multiple elements of the same type in contiguous memory locations, while a pointer variable stores the address of another variable. The summary demonstrates how to declare and initialize arrays and pointers, access array elements using pointers, pass arrays to functions by reference using pointers, and how pointers and arrays are related but not synonymous concepts.
A pointer is a variable that stores the memory address of another variable. Pointers allow functions to modify variables in the caller and are useful for handling arrays and dynamic memory allocation. Pointers contain the address of the memory location they point to. Pointer variables can be declared to hold these memory addresses and can then be used to indirectly access the value at the addressed location.
This document provides an overview of pointers in C programming. It defines pointers as variables that store memory addresses rather than values. Pointers have several useful applications like accessing variables outside functions, passing information between functions, and more efficiently handling data tables. The document explains how to declare pointer variables, assign the address of a variable to a pointer, dereference a pointer to access the value at an address, and pass pointers to functions. It also discusses pointers and arrays, structures, and arrays of structures.
Hamid Milton Mansaray teaches the chapter on arrays, pointers, and strings in week 8. Some key points covered include initializing and accessing elements of one-dimensional arrays using indexing or pointers, passing arrays to functions by reference using pointers, pointer arithmetic and comparing pointers, dynamic memory allocation for arrays using calloc and malloc, and how strings are implemented as character arrays in C with a null terminator. Examples are provided for summing arrays, merging sorted arrays, and basic pointer operations.
A pointer is a variable that stores the memory address of another variable. Pointers allow accessing and modifying the data stored at the referenced memory location. Pointers can be declared by specifying the data type followed by an asterisk, and are initialized by assigning the address of a variable to the pointer variable. Pointer variables can be used in expressions and arithmetic and can be passed to functions to modify the referenced data. Arrays can also be accessed and traversed using pointers by treating the array name as a pointer to its first element. Pointers to functions allow functions to be passed as arguments and enables polymorphism.
- A pointer is a variable that stores the address of another variable. Pointers allow dynamic memory allocation and access to the value of the variable being pointed to using the indirection operator (*).
- Pointer variables are declared with a data type followed by an asterisk, such as int *ptr. They can be initialized by using the address-of operator (&) to store the address of another variable.
- Pointers can be used to access elements in an array by using pointer arithmetic. An array name itself is a constant pointer to the first element of the array.
Homework Assignment – Array Technical DocumentWrite a technical .pdfaroraopticals15
Homework Assignment – Array Technical Document
Write a technical document that describes the structure and use of arrays. The document should
be 3 to 5 pages and include an Introduction section, giving a brief synopsis of the document and
arrays, a Body section, describing arrays and giving an annotated example of their use as a
programming construct, and a conclusion to revisit important information about arrays described
in the Body of the document. Some suggested material to include:
Declaring arrays of various types
Array pointers
Printing and processing arrays
Sorting and searching arrays
Multidimensional arrays
Indexing arrays of various dimension
Array representation in memory by data type
Passing arrays as arguments
If you find any useful images on the Internet, you can use them as long as you cite the source in
end notes.
Solution
Array is a collection of variables of the same type that are referenced by a common name.
Specific elements or variables in the array are accessed by means of index into the array.
If taking about C, In C all arrays consist of contiguous memory locations. The lowest address
corresponds to the first element in the array while the largest address corresponds to the last
element in the array.
C supports both single and multi-dimensional arrays.
1) Single Dimension Arrays:-
Syntax:- type var_name[size];
where type is the type of each element in the array, var_name is any valid identifier, and size is
the number of elements in the array which has to be a constant value.
*Array always use zero as index to first element.
The valid indices for array above are 0 .. 4, i.e. 0 .. number of elements - 1
For Example :- To load an array with values 0 .. 99
int x[100] ;
int i ;
for ( i = 0; i < 100; i++ )
x[i] = i ;
To determine to size of an array at run time the sizeof operator is used. This returns the size in
bytes of its argument. The name of the array is given as the operand
size_of_array = sizeof ( array_name ) ;
2) Initialisg array:-
Arrays can be initialised at time of declaration in the following manner.
type array[ size ] = { value list };
For Example :-
int i[5] = {1, 2, 3, 4, 5 } ;
i[0] = 1, i[1] = 2, etc.
The size specification in the declaration may be omitted which causes the compiler to count the
number of elements in the value list and allocate appropriate storage.
For Example :- int i[ ] = { 1, 2, 3, 4, 5 } ;
3) Multidimensional array:-
Multidimensional arrays of any dimension are possible in C but in practice only two or three
dimensional arrays are workable. The most common multidimensional array is a two
dimensional array for example the computer display, board games, a mathematical matrix etc.
Syntax :type name [ rows ] [ columns ] ;
For Example :- 2D array of dimension 2 X 3.
int d[ 2 ] [ 3 ] ;
A two dimensional array is actually an array of arrays, in the above case an array of two integer
arrays (the rows) each with three elements, and is stored row-wise in memory.
For Example :- Program to fill .
The document discusses pointers in C programming. It defines pointers as variables that contain memory addresses and can point to different data types. It covers pointer arithmetic, passing pointers to functions, and using pointers with arrays, including arrays of pointers. Functions can be called by value by passing the variable itself, or by reference by passing the memory address of the variable using pointers, allowing the function to modify the original variable. Pointer notation can be used to access elements of two-dimensional arrays.
The document discusses pointers and arrays in C programming. It explains that an array stores multiple elements of the same type in contiguous memory locations, while a pointer variable stores the address of another variable. The summary demonstrates how to declare and initialize arrays and pointers, access array elements using pointers, pass arrays to functions by reference using pointers, and how pointers and arrays are related but not synonymous concepts.
Pointers allow programs to indirectly reference memory locations. They store the address of another variable. Pointers are used to pass variables by reference, dynamically allocate memory, and build complex data structures like linked lists. Pointer variables are declared with a type followed by an asterisk (e.g. int *ptr). The ampersand (&) operator returns the address of its operand. The indirection (*) operator accesses the value at the address a pointer refers to. Pointers can be passed as function parameters or returned as values. Dynamic memory allocation with functions like malloc, calloc, and realloc allow programs to request memory at runtime.
Pointers provide references to memory locations in a program. They are used to pass variables by reference, access array elements, and dynamically allocate memory. A pointer variable contains the address of another variable. The address (&) operator returns the memory address of a variable. The indirection (*) operator accesses the value of the variable a pointer is pointing to. Pointers allow modifying variables passed to functions and returning addresses from functions. Memory is dynamically allocated using functions like malloc(), calloc(), and realloc() and freed using free(). Multidimensional arrays can be dynamically allocated by allocating an array of pointers and having each pointer point to a 1D array.
This document discusses data structures and arrays. It covers one-dimensional arrays, how they are initialized and indexed, and their relationship to pointers. Pointers can be used to reference array elements, and arrays can be passed as arguments to functions by passing their address. The document also provides examples of using arrays, including an example of bubble sort to sort an array and examples of dynamically allocating memory for arrays using calloc() and malloc().
The document discusses arrays and strings in C programming. It covers topics like declaring and initializing single and multi-dimensional arrays, accessing array elements, passing arrays to functions, and common array operations like sorting, calculating average and standard deviation. Strings are also introduced as arrays of characters terminated by a null character. Examples are provided for many array concepts and operations.
INDIAN INSTITUTE OF TECHNOLOGY KANPUR ESC 111M Lec12.pptxAbhimanyuChaure
This is a presentation of c programming which is taught at indian institute of technology kanpur in the first year first semester under the bachelor of technology or bachelor of science programme. ESC basically refers to the fundamentals of computing which here the course is taught by professors under computer science department. Here tutorials are also conducted where tutor comes and solves the doubts of students. To practice programming iit kanpur has its own platform called prutor where all the lab work and practice is done. The content which is taught here is of very good level. To take admission in indian institute of technology of kanpur you have to give joint entrance examination . first you have to give jee mains and then give jee advanced. Well jee advanced is the the toughest exams in the world. Because difficult questions from physics chemistry and maths are asked in it.
This document provides information about linear search of arrays in C++. It discusses:
- Linear search involves comparing each element of an array to a key value to find a match. It is useful for small, unsorted arrays but is inefficient as it must examine every element if the key is not present.
- The linearSearch function takes an array, search key, and array size as parameters. It uses a for loop to compare each element to the key and returns the index of the match, or -1 if no match is found.
- Multiple examples are provided to demonstrate calling the linearSearch function and displaying the results of searches that do and do not find the key.
The document discusses various aspects of arrays in C programming, including:
- Declaring and initializing one-dimensional arrays
- Accessing array elements using pointers and indexes
- Declaring and initializing two-dimensional arrays
- Passing arrays to functions by passing the base address
- Declaring arrays of pointers where each element is a pointer variable
An array is a collection of similar elements that are stored in contiguous memory locations. Arrays in C can have one or more dimensions. One-dimensional arrays are declared with the type of elements, name of the array, and number of elements within brackets (e.g. int marks[30]). Multi-dimensional arrays represent matrices and are declared with the number of rows and columns (e.g. int arr[5][10]). Individual elements within an array are accessed via indices (e.g. arr[2][7]). Pointers in C are related to arrays - the name of an array represents the address of its first element, and pointer arithmetic can be used to access successive elements in an array.
Pointers in C programming store the address of other variables or memory locations. Pointers allow accessing and manipulating the data stored at those memory addresses. Pointers are useful for accessing arrays, dynamically allocating memory, and passing arguments by reference. Pointer variables must be declared with a data type and dereferenced using the * operator. Pointers can be initialized by assigning the address of another variable using the & operator. Pointer arithmetic allows incrementing or decrementing pointers to access successive memory locations.
C++ - UNIT_-_IV.pptx which contains details about PointersANUSUYA S
Pointer is a variable in C++ that holds the address of another variable. Pointers allow accessing the memory location of other variables. There are different types of pointers based on the data type they are pointing to such as integer, character, class etc. Pointers are declared using an asterisk * before the pointer variable name. The address of a variable can be assigned to a pointer using the & address of operator. Pointers can be used to access members of a class and pass arrays to functions. The this pointer represents the address of the object inside member functions. Virtual functions allow dynamic binding at runtime in inheritance.
This document provides information on arrays, structures, and pointers in C++. It defines an array as a collection of data storage locations that hold the same type of data. Arrays can be one-dimensional or multi-dimensional. Structures are collections of variables of different data types grouped together under a single name. Pointers are variables that store the address of another variable in memory. Pointers can be used to access elements in an array using pointer arithmetic and to dynamically allocate memory using operators like new and delete.
The document discusses pointers in C++. Some key points:
- Pointers store the address of a variable in memory. They can be used to access values indirectly through dereferencing.
- Common pointer operations include address-of (&) and dereference (*) operators.
- Pointers allow passing by reference, reducing code and improving performance when used with arrays, structures, and functions.
- Examples demonstrate declaring and using pointers to swap values without a third variable, and to access array elements indirectly through pointers.
Pointers in C allow variables to hold the memory addresses of other variables and data types. Pointers use the asterisk (*) and ampersand (&) operators - * accesses the value at a memory address, while & returns the memory address of a variable. Pointers are useful for passing arguments to functions, returning multiple values from functions, and accessing arrays through a single pointer variable. Pointer arithmetic increments or decrements a pointer by the size of its data type. Pointer-to-pointers allow pointers to hold the addresses of other pointer variables. Proper initialization and boundary checking is important to avoid crashes with pointers.
ESC112 Course lecture slides on pointers and memory allocation.pptxkrishna50blogging
This document discusses pointers and memory allocation in C. It covers pointer declaration syntax, dereferencing pointers, pointer arithmetic, pointers and arrays, using pointers with strings, and functions for dynamic memory allocation like malloc(), calloc(), and realloc(). Pointers allow accessing and modifying values in memory by their address rather than by name. Pointer arithmetic allows treating arrays as contiguous blocks of memory. Dynamic allocation functions return memory addresses that can be accessed via pointers.
This document discusses arrays and strings in C++. It defines an array as a collection of identical data objects stored in consecutive memory locations under a common name. Arrays allow storing multiple values of the same type using one variable name. Strings are represented using arrays of character type (char). Strings are terminated with a null character (\0) to indicate the end of the valid characters. Arrays and strings can be initialized using individual values or constant strings enclosed in double quotes. Arrays and strings share properties like indexing elements from 0 to size-1.
Pointers allow programs to store and manipulate memory addresses. A pointer variable contains the address of another variable. Pointers are useful for passing data between functions, returning multiple values from functions, and dynamically allocating memory at runtime. Pointers can also be used to access elements of arrays indirectly and implement multidimensional arrays more efficiently. Pointer notation provides an alternative way to access array elements through pointer arithmetic rather than subscripts.
The document discusses various aspects of arrays in C programming language. It defines arrays as collections of similar data types stored in contiguous memory locations. It describes single dimensional and multi-dimensional arrays. It also discusses array declaration and initialization syntax. Some key points covered are: advantages of arrays over single variables, accessing array elements using indexes, passing arrays to functions, and two dimensional or 2D arrays also called matrices.
The document provides an overview of arrays in Java, including:
- Arrays can hold multiple values of the same type, unlike primitive variables which can only hold one value.
- One-dimensional arrays use a single index, while multi-dimensional arrays use two or more indices.
- Elements in an array are accessed using their index number, starting from 0.
- The size of an array is set when it is declared and cannot be changed, but reference variables can point to different arrays.
- Common operations on arrays include initializing values, accessing elements, looping through elements, and copying arrays.
The document describes text mining and web mining. It discusses the need for text mining due to the large amount of unstructured data organizations hold. It differentiates between text mining, web mining, and data mining. The document outlines the text mining process of establishing a corpus from unstructured data sources, introducing structure to create a term-document matrix, and extracting knowledge from the matrix. It also discusses applications of text mining in domains like security, medicine, marketing, and academics.
This document summarizes several routing protocols for ad hoc wireless networks. It describes the challenges in this domain including dynamic topologies and limited resources. It then categorizes and explains several types of routing protocols, including proactive protocols like DSDV, reactive protocols like AODV and DSR, hybrid protocols like ZRP, and geographic routing. It provides details on the route discovery and maintenance mechanisms of some of these prominent protocols. It also discusses theoretical limits on network capacity and the impact of mobility and hierarchy.
Pointers allow programs to indirectly reference memory locations. They store the address of another variable. Pointers are used to pass variables by reference, dynamically allocate memory, and build complex data structures like linked lists. Pointer variables are declared with a type followed by an asterisk (e.g. int *ptr). The ampersand (&) operator returns the address of its operand. The indirection (*) operator accesses the value at the address a pointer refers to. Pointers can be passed as function parameters or returned as values. Dynamic memory allocation with functions like malloc, calloc, and realloc allow programs to request memory at runtime.
Pointers provide references to memory locations in a program. They are used to pass variables by reference, access array elements, and dynamically allocate memory. A pointer variable contains the address of another variable. The address (&) operator returns the memory address of a variable. The indirection (*) operator accesses the value of the variable a pointer is pointing to. Pointers allow modifying variables passed to functions and returning addresses from functions. Memory is dynamically allocated using functions like malloc(), calloc(), and realloc() and freed using free(). Multidimensional arrays can be dynamically allocated by allocating an array of pointers and having each pointer point to a 1D array.
This document discusses data structures and arrays. It covers one-dimensional arrays, how they are initialized and indexed, and their relationship to pointers. Pointers can be used to reference array elements, and arrays can be passed as arguments to functions by passing their address. The document also provides examples of using arrays, including an example of bubble sort to sort an array and examples of dynamically allocating memory for arrays using calloc() and malloc().
The document discusses arrays and strings in C programming. It covers topics like declaring and initializing single and multi-dimensional arrays, accessing array elements, passing arrays to functions, and common array operations like sorting, calculating average and standard deviation. Strings are also introduced as arrays of characters terminated by a null character. Examples are provided for many array concepts and operations.
INDIAN INSTITUTE OF TECHNOLOGY KANPUR ESC 111M Lec12.pptxAbhimanyuChaure
This is a presentation of c programming which is taught at indian institute of technology kanpur in the first year first semester under the bachelor of technology or bachelor of science programme. ESC basically refers to the fundamentals of computing which here the course is taught by professors under computer science department. Here tutorials are also conducted where tutor comes and solves the doubts of students. To practice programming iit kanpur has its own platform called prutor where all the lab work and practice is done. The content which is taught here is of very good level. To take admission in indian institute of technology of kanpur you have to give joint entrance examination . first you have to give jee mains and then give jee advanced. Well jee advanced is the the toughest exams in the world. Because difficult questions from physics chemistry and maths are asked in it.
This document provides information about linear search of arrays in C++. It discusses:
- Linear search involves comparing each element of an array to a key value to find a match. It is useful for small, unsorted arrays but is inefficient as it must examine every element if the key is not present.
- The linearSearch function takes an array, search key, and array size as parameters. It uses a for loop to compare each element to the key and returns the index of the match, or -1 if no match is found.
- Multiple examples are provided to demonstrate calling the linearSearch function and displaying the results of searches that do and do not find the key.
The document discusses various aspects of arrays in C programming, including:
- Declaring and initializing one-dimensional arrays
- Accessing array elements using pointers and indexes
- Declaring and initializing two-dimensional arrays
- Passing arrays to functions by passing the base address
- Declaring arrays of pointers where each element is a pointer variable
An array is a collection of similar elements that are stored in contiguous memory locations. Arrays in C can have one or more dimensions. One-dimensional arrays are declared with the type of elements, name of the array, and number of elements within brackets (e.g. int marks[30]). Multi-dimensional arrays represent matrices and are declared with the number of rows and columns (e.g. int arr[5][10]). Individual elements within an array are accessed via indices (e.g. arr[2][7]). Pointers in C are related to arrays - the name of an array represents the address of its first element, and pointer arithmetic can be used to access successive elements in an array.
Pointers in C programming store the address of other variables or memory locations. Pointers allow accessing and manipulating the data stored at those memory addresses. Pointers are useful for accessing arrays, dynamically allocating memory, and passing arguments by reference. Pointer variables must be declared with a data type and dereferenced using the * operator. Pointers can be initialized by assigning the address of another variable using the & operator. Pointer arithmetic allows incrementing or decrementing pointers to access successive memory locations.
C++ - UNIT_-_IV.pptx which contains details about PointersANUSUYA S
Pointer is a variable in C++ that holds the address of another variable. Pointers allow accessing the memory location of other variables. There are different types of pointers based on the data type they are pointing to such as integer, character, class etc. Pointers are declared using an asterisk * before the pointer variable name. The address of a variable can be assigned to a pointer using the & address of operator. Pointers can be used to access members of a class and pass arrays to functions. The this pointer represents the address of the object inside member functions. Virtual functions allow dynamic binding at runtime in inheritance.
This document provides information on arrays, structures, and pointers in C++. It defines an array as a collection of data storage locations that hold the same type of data. Arrays can be one-dimensional or multi-dimensional. Structures are collections of variables of different data types grouped together under a single name. Pointers are variables that store the address of another variable in memory. Pointers can be used to access elements in an array using pointer arithmetic and to dynamically allocate memory using operators like new and delete.
The document discusses pointers in C++. Some key points:
- Pointers store the address of a variable in memory. They can be used to access values indirectly through dereferencing.
- Common pointer operations include address-of (&) and dereference (*) operators.
- Pointers allow passing by reference, reducing code and improving performance when used with arrays, structures, and functions.
- Examples demonstrate declaring and using pointers to swap values without a third variable, and to access array elements indirectly through pointers.
Pointers in C allow variables to hold the memory addresses of other variables and data types. Pointers use the asterisk (*) and ampersand (&) operators - * accesses the value at a memory address, while & returns the memory address of a variable. Pointers are useful for passing arguments to functions, returning multiple values from functions, and accessing arrays through a single pointer variable. Pointer arithmetic increments or decrements a pointer by the size of its data type. Pointer-to-pointers allow pointers to hold the addresses of other pointer variables. Proper initialization and boundary checking is important to avoid crashes with pointers.
ESC112 Course lecture slides on pointers and memory allocation.pptxkrishna50blogging
This document discusses pointers and memory allocation in C. It covers pointer declaration syntax, dereferencing pointers, pointer arithmetic, pointers and arrays, using pointers with strings, and functions for dynamic memory allocation like malloc(), calloc(), and realloc(). Pointers allow accessing and modifying values in memory by their address rather than by name. Pointer arithmetic allows treating arrays as contiguous blocks of memory. Dynamic allocation functions return memory addresses that can be accessed via pointers.
This document discusses arrays and strings in C++. It defines an array as a collection of identical data objects stored in consecutive memory locations under a common name. Arrays allow storing multiple values of the same type using one variable name. Strings are represented using arrays of character type (char). Strings are terminated with a null character (\0) to indicate the end of the valid characters. Arrays and strings can be initialized using individual values or constant strings enclosed in double quotes. Arrays and strings share properties like indexing elements from 0 to size-1.
Pointers allow programs to store and manipulate memory addresses. A pointer variable contains the address of another variable. Pointers are useful for passing data between functions, returning multiple values from functions, and dynamically allocating memory at runtime. Pointers can also be used to access elements of arrays indirectly and implement multidimensional arrays more efficiently. Pointer notation provides an alternative way to access array elements through pointer arithmetic rather than subscripts.
The document discusses various aspects of arrays in C programming language. It defines arrays as collections of similar data types stored in contiguous memory locations. It describes single dimensional and multi-dimensional arrays. It also discusses array declaration and initialization syntax. Some key points covered are: advantages of arrays over single variables, accessing array elements using indexes, passing arrays to functions, and two dimensional or 2D arrays also called matrices.
The document provides an overview of arrays in Java, including:
- Arrays can hold multiple values of the same type, unlike primitive variables which can only hold one value.
- One-dimensional arrays use a single index, while multi-dimensional arrays use two or more indices.
- Elements in an array are accessed using their index number, starting from 0.
- The size of an array is set when it is declared and cannot be changed, but reference variables can point to different arrays.
- Common operations on arrays include initializing values, accessing elements, looping through elements, and copying arrays.
The document describes text mining and web mining. It discusses the need for text mining due to the large amount of unstructured data organizations hold. It differentiates between text mining, web mining, and data mining. The document outlines the text mining process of establishing a corpus from unstructured data sources, introducing structure to create a term-document matrix, and extracting knowledge from the matrix. It also discusses applications of text mining in domains like security, medicine, marketing, and academics.
This document summarizes several routing protocols for ad hoc wireless networks. It describes the challenges in this domain including dynamic topologies and limited resources. It then categorizes and explains several types of routing protocols, including proactive protocols like DSDV, reactive protocols like AODV and DSR, hybrid protocols like ZRP, and geographic routing. It provides details on the route discovery and maintenance mechanisms of some of these prominent protocols. It also discusses theoretical limits on network capacity and the impact of mobility and hierarchy.
The document provides an overview of sensor networks, which consist of low-cost, low-power sensor devices that can collect, process, analyze, and disseminate data from various environments. Sensor networks enable information gathering and processing through reliable monitoring using small, wireless sensor nodes. Key challenges for sensor networks include extending the lifetime of the network given limited energy resources and adapting to changing topologies as nodes fail or move. Sensor networks operate using self-organizing, multi-hop wireless connections between nodes that coordinate sensing tasks and route data back to central access points.
This document provides an introduction to data mining concepts and techniques. It defines data mining as the extraction of implicit, previously unknown, and potentially useful patterns from large amounts of data. The document outlines the data mining process and how data mining draws upon multiple disciplines including database technology, statistics, machine learning, and visualization. It also describes common data mining functionalities like classification, clustering, association rule mining, and discusses some of the most popular data mining algorithms.
The document provides an introduction to data mining, including why it is used from both commercial and scientific viewpoints. It discusses how much data is being collected and stored, and how data mining can help make sense of large datasets that would be impossible for humans to analyze alone. It describes some of the largest databases in the world and different data mining tasks like classification, regression, clustering, and association rule learning. Examples are given for how data mining can be applied to problems like credit risk assessment, fraud detection, customer churn prediction, and direct marketing.
This document provides an overview of a data mining course. It discusses that the course will be taught by George Kollios and will cover topics like data warehouses, association rule mining, clustering, classification, and advanced topics. It also outlines the grading breakdown and schedule. Additionally, it defines data mining and describes common data mining tasks like classification, clustering, and association rule mining. It provides examples of applications and discusses the data mining process.
An IP address is a unique number that identifies a device on a network. IP stands for Internet Protocol, which defines the format for sending data over the internet or networks. IP addresses contain location information and allow devices to communicate by identifying the destination address. They are divided into a network and host part, and can be represented in decimal or binary notation. IPv4 is currently used, while IPv6 is an upcoming replacement that improves on IPv4. IP addresses can be public, assigned by ISPs, or private for internal networks.
The document describes a chapter about the application layer from a textbook on computer networking. It covers several topics:
1. An introduction to the application layer including common network applications, client-server and peer-to-peer architectures, and how processes communicate over the network.
2. Descriptions of the HTTP and TCP protocols that are commonly used at the application layer. HTTP uses the TCP transport layer to provide reliable data transfer for web applications.
3. An overview of how non-persistent and persistent HTTP connections work, with persistent connections allowing multiple objects to be transferred over a single TCP connection between a client and server.
MOBILE & WIRELESS SECURITY And MOBILE & WIRELESS SECURITYDEEPAK948083
This document provides an overview of mobile and wireless security. It discusses the need for security as wireless networks become more prevalent and outlines some common security threats like spoofing, sniffing, tampering and theft. It then describes various security technologies used to address these threats, including cryptography, digital certificates, digital signatures and public key infrastructure. Specific security protocols like SSL, TLS and IPSec are also mentioned. The document emphasizes that securing wireless networks requires considering authentication, data integrity, confidentiality, authorization and non-repudiation across the entire environment.
This document provides an introduction to data structures presented by Prof. K. Adisesha. It defines data structures as representations of logical relationships between data elements that consider both the elements and their relationships. Data structures affect both structural and functional aspects of programs. They are classified as primitive or non-primitive, with primitive structures operated on directly by machine instructions and non-primitive structures derived from primitive ones. Linear data structures like stacks and queues have elements in sequence, while non-linear structures like trees and graphs have hierarchical or parent-child relationships. Common operations on data structures include traversal, insertion, selection, searching, sorting, merging, and deletion. Arrays are also discussed in detail as a fundamental data structure.
This document discusses different types of malicious code such as viruses, Trojan horses, logic bombs, and worms. It defines each type and provides examples. Viruses can attach to programs by appending code, surrounding code, or integrating with/replacing code. They gain control by overwriting targets or changing pointers. Common places for viruses include boot sectors, system files, and memory-resident programs. Viruses can be detected through their storage patterns, execution patterns, and transmission patterns. Prevention methods include using trusted software sources, testing new software in isolation, and regularly using virus detectors.
1) Elliptic curve cryptography uses elliptic curves over finite fields to provide a method for constructing cryptographic groups.
2) The security of elliptic curve cryptography relies on the difficulty of solving the elliptic curve discrete logarithm problem.
3) Elliptic curve cryptography provides the same security level as other cryptosystems like RSA but with smaller key sizes, making it advantageous for applications with limited computational power or space.
Block ciphers encrypt fixed-length blocks of plaintext into ciphertext using symmetric keys. There are five modes of operation that allow block ciphers to encrypt messages longer than the block size: electronic codebook (ECB), cipher block chaining (CBC), cipher feedback (CFB), output feedback (OFB), and counter mode. These modes address issues like encrypting non-block-sized messages and adding randomness to prevent patterns in the ciphertext. ECB encrypts each block independently while the others use chaining or a counter to make each ciphertext block dependent on previous blocks. Initialization vectors are used to randomize encryption of identical plaintexts.
Elliptic curve cryptography uses elliptic curves over finite fields to provide security for encryption, digital signatures, and key exchange. The security of ECC relies on the difficulty of solving the elliptic curve discrete logarithm problem. ECC offers equivalent security to RSA and other systems using smaller key sizes, reducing requirements for storage, transmission, and processing. Implementation considerations include optimization of finite field and elliptic curve arithmetic for different computing environments and applications.
The document provides an introduction to data structures and algorithms. It begins with basic concepts like data, data types, data objects, and data structures. It then discusses different types of data structures like linear and non-linear, static and dynamic, and persistent and ephemeral data structures. The document also explains common data structures like arrays, stacks, queues, linked lists, trees and graphs. It provides examples to illustrate concepts like one dimensional, two dimensional and multi-dimensional arrays. Finally, it presents code examples to generate Fibonacci series using both iterative and recursive functions.
This document discusses laws, regulations, ethics, and professional organizations related to information security. It defines key concepts like laws, ethics, liability, due care and due diligence. Major sections cover relevant US laws, privacy laws, types of laws, and international legal issues. Professional ethics organizations and their codes are also summarized.
This document contains slides from a chapter on principles of information security. It discusses how laws are based on ethics, and different types of relevant laws in the US and other countries. These include privacy laws, copyright laws, and export/espionage laws. It also discusses ethics in information security, cultural differences, and professional organizations that promote ethics through codes of conduct and certifications. The role of education and deterrence to promote ethical behavior is covered.
IPSec provides security services like data integrity, authentication and confidentiality. It uses protocols like AH and ESP to implement these services in transport or tunnel mode. The IPSec architecture includes security policy and security association databases that define how security is applied to packets. SSL/TLS works above the transport layer, using a handshake protocol to authenticate parties and negotiate encryption, before applying its record protocol to provide message integrity and confidentiality. IDS/IPS systems monitor networks for malicious activity, generate alerts and reports. Signature and anomaly-based methods are used to detect known and unknown threats. IPS systems also aim to prevent detected threats from succeeding.
The document discusses stacks and their applications. It defines a stack as a Last In First Out (LIFO) data structure. Key stack operations are described such as push, pop, and peek. An array implementation of a stack is presented and applications like checking balanced brackets, converting infix to postfix notation, and postfix calculators are covered. Example code and diagrams are provided to illustrate stack concepts and operations.
The document discusses traversing a binary tree without recursion. It describes using an activation stack to simulate recursion by tracking the nodes to visit at each level of the tree. It provides pseudocode for in-order, pre-order and post-order traversal algorithms using an activation stack instead of recursion. It also covers inserting nodes into a binary search tree by recursively finding the correct location to add new nodes while maintaining the tree's search properties.
Open Source Contributions to Postgres: The Basics POSETTE 2024ElizabethGarrettChri
Postgres is the most advanced open-source database in the world and it's supported by a community, not a single company. So how does this work? How does code actually get into Postgres? I recently had a patch submitted and committed and I want to share what I learned in that process. I’ll give you an overview of Postgres versions and how the underlying project codebase functions. I’ll also show you the process for submitting a patch and getting that tested and committed.
Enhanced data collection methods can help uncover the true extent of child abuse and neglect. This includes Integrated Data Systems from various sources (e.g., schools, healthcare providers, social services) to identify patterns and potential cases of abuse and neglect.
1. C Arrays and Pointers
• In Java, pointers are easy to deal with
– In fact, there is little that can go wrong in Java since
pointer access is done for you
• the only exception is in passing an object to a method without
knowing if the method will change the object or not (for
instance, Strings cannot be changed in a method like concat)
• In C, pointers are more challenging
– You will need to know
• when to use a pointer
• when to dereference the pointer
• when to pass an address of a variable rather than the variable
itself
• when to use pointer arithmetic to change the pointer
• how to use pointers without making your programs unreadable
– Basically, you have to learn how to not “shoot yourself
in the foot” with pointers
2. The Basics
• A pointer is merely an address of where a datum or structure is
stored
– all pointers are typed based on the type of entity that they point to
– to declare a pointer, use * preceding the variable name as in int *x;
• To set a pointer to a variable’s address use & before the variable
as in x = &y;
– & means “return the memory address of”
– in this example, x will now point to y, that is, x stores y’s address
• If you access x, you merely get the address
• To get the value that x points to, use * as in *x
– *x = *x + 1; will add 1 to y
• * is known as the indirection (or dereferencing) operator because
it requires a second access
– that is, this is a form of indirect addressing
3. Example Code
int x = 1, y = 2, z[10];
int *ip; // ip is a pointer to an int, so it can point to x, y, or an element of z
ip = &x; // ip now points at the location where x is stored
y = *ip; // set y equal to the value pointed to by ip, or y = x
*ip = 0; // now change the value that ip points to to 0, so now x = 0
// but notice that y is unchanged
ip = &z[0]; // now ip points at the first location in the array z
*ip = *ip + 1; // the value that ip points to (z[0]) is incremented
int x, *y, z, *q;
x = 3;
y = &x; // y points to x
printf("%dn", x); // outputs 3
printf("%dn", y); // outputs x’s address, will seem like a random number to us
printf("%dn", *y); // outputs what y points to, or x (3)
printf("%dn", *y+1); // outputs 4 (print out what y points to + 1)
printf("%dn", *(y+1)); // this outputs the item after x in memory – what is it?
z = *(&x); // z equals 3 (what &x points to, which is x)
q = &*y; // q points to 3 – note *& and &* cancel out
4. Arrays and Pointers
• We declare an array using [ ] in our declaration following the variable name
– int x[5]; // unlike Java, we can’t do int[ ] x;
• You must include the size of the array in the [ ] when declaring unless you are
also initializing the array to its starting values as in:
– int x [ ] = {1, 2, 3, 4, 5};
– you can also include the size when initializing as long as the size is >= the
number of items being initialized (in which case the remaining array elements are
uninitialized)
• As in Java
– you access array elements just as in Java as in x[4]
– array indices start at 0
– arrays can be passed as parameters, the type being received would be denoted as
int x[ ]
• Arrays in C are interesting because they are pointed to
– the variable that you declare for the array is actually a pointer to the first array
element
• You can interact with the array elements either through pointers or by using [
]
• One of the intriguing features of pointers in C is the ability to manipulate the
pointers through pointer arithmetic – a pointer is an int value, so we can add
or subtract
– this will be used for stepping through arrays rather than using array indices
5. Using Pointers with Arrays
• Recall in an earlier example, we did
ip = &z[0];
• This sets our pointer to point at the
first element of the array
– In fact, z is a pointer as well and
we can access z[0] either using
z[0], *ip, or *z
• What about accessing z[1]?
– We can do z[1] as usual, or we
can add 1 to the location pointed
to by ip or z, that is *(ip+1) or
*(z+1)
– While we can reset ip to be ip =
ip+1, we cannot reset z to be z =
z+1
– adding 1 to ip will point to z[1],
but if z = z + 1 were legal, we
would lose access to the first
array location since z is our
array variable
• Notice that ip=ip+1 (or ip++)
moves the pointer 4 bytes
instead of 1 to point at the next
array location
– The amounted added to the pointer
is based on the size of the array
element
• 8 for an array of doubles
• 1 for an array of chars (strings)
• 4 for an array of ints
• We can declare our arrays using
pointers instead of [ ]
– notably, we might do this for our
formal parameters as this better
describes what we are dealing with)
– for instance, function1(int *array)
rather than function1(int[ ] array)
– We wouldn’t normally do this to
declare our arrays as the array’s
pointer exists but not the array
itself
6. Iterating Through the Array
• Here we see two ways to iterate through an array, the usual way,
but also a method using pointer arithmetic
• Let’s consider the code on the right:
– pj is a pointer to an int
– We start with pj pointing at a, that is, pj points to a[0]
– The loop iterates while pj < a + n
• pj is a pointer, so it is an address
• a is a pointer to the beginning of an array of n elements so a + n is the size of the
array
• pj++ increments the pointer to point at the next element in the array
• The instruction (*pj)++ says “take what pj points to and increment it”
– NOTE: (*pj)++; increments what pj points to, *(pj++); increments the
pointer to point at the next array element
• what do each of these do? *pj++; ++*pj;
int j;
for(j = 0; j < n; j++)
a[j]++;
int *pj;
for(pj = a; pj < a + n; pj++)
(*pj)++;
7. Array Example Using a Pointer
int x[4] = {12, 20, 39, 43}, *y;
y = &x[0]; // y points to the beginning of the array
printf("%dn", x[0]); // outputs 12
printf("%dn", *y); // also outputs 12
printf("%dn", *y+1); // outputs 13 (12 + 1)
printf("%dn", (*y)+1); // also outputs 13
printf("%dn", *(y+1)); // outputs x[1] or 20
y+=2; // y now points to x[2]
printf("%dn", *y); // prints out 39
*y = 38; // changes x[2] to 38
printf("%dn", *y-1); // prints out x[2] - 1 or 37
*y++; // sets y to point at the next array element
printf("%dn", *y); // outputs x[3] (43)
(*y)++; // sets what y points to to be 1 greater
printf("%dn", *y); // outputs the new value of x[3] (44)
8. Strings
• There is no string type, we implement strings as arrays of chars
– char str[10]; // str is an array of 10 chars or a string
– char *str; // str points to the beginning of a string of unspecified
length
• There is a string.h library with numerous string functions
– they all operate on arrays of chars and include:
• strcpy(s1, s2) – copies s2 into s1 (including ‘0’ as last char)
• strncpy(s1, s2, n) – same but only copies up to n chars of s2
• strcmp(s1, s2) – returns a negative int if s1 < s2, 0 if s1 = = s2 and a positive
int if s1 > s2
• strncmp(s1, s2, n) – same but only compares up to n chars
• strcat(s1, s2) – concatenates s2 onto s1 (this changes s1, but not s2)
• strncat(s1, s2, n) – same but only concatenates up to n chars
• strlen(s1) – returns the integer length of s1
• strchr(s1, ch) – return a pointer to the first occurrence of ch in s1 (or NULL if
ch is not present)
• strrchr(s1, ch) – same but the pointer points to the last occurrence of ch
• strpbrk(s1, s2) – return a pointer to the first occurrence of any character in s1
that matches a character in s2 (or NULL if none are present)
• strstr(s1, s2) – substring, return a pointer to the char in s1 that starts a substring
that matches s2, or NULL if the substring is not present
9. Implementing Some of These
int strlen(char *s)
{
int n;
for(n = 0; *s != ‘0’; s++)
n++;
return n;
}
void strcpy(char *s, char *t)
{
while((*s = *t) != ‘0’)
{
s++; t++;
}
}
void strcpy(char *s, char *t)
{
while((*s++ = *t++) != ‘0’);
}
void strcpy(char *s, char *t)
{
int i = 0;
while((s[i] = t[i]) != ‘0’)
i++;
}
int strcmp(char *s, char *t)
{
int i;
for(i=0;s[i] = = t[i];i++)
if(s[i] = = ‘0’)
return 0;
return s[i] – t[i];
}
Notice in the second
strcmp and second
and third strcpy the
use of pointers to iterate
through the strings
The conciseness of the last strcmp and strcpy make them
hard to understand
int strcmp(char *s, char *t)
{
for( ; *s = = *t; s++, t++)
if(*s = = ‘0’) return 0;
return *s - *t;
}
10. More On Pointer Arithmetic
• We can also perform subtraction on pointers
• Here, we pass to a function the address of the third
element of an array (&a[2]) and use pointer subtraction to
get to a[0] and a[1])
int a[10] = {…};
int *ip;
for(ip = &a[9]; ip >= a; ip--)
…
int a[3] = {…};
printf(“%d”, addem(&a[2]));
int addem(int *ip)
{
int temp;
temp = *ip + *(ip – 1) + *(ip – 2);
return temp;
}
Recall:
a[0] = *a and
a[i] = *(a + i)
If a is an array, and p = &a[0] then we can reference array
elements as a[i], *(p+i), but we can also reference them as
p[i] and *(a+i) – that is, a and p are both pointers to the array
And can be dereferenced by * or by [ ]
11. Multidimensional Arrays
• As in Java, C allows multidimensional arrays by using more [ ]
– Example: int matrix[5][10];
• Some differences:
– Because functions can be compiled separately, we must denote all but one
dimension of a multiple dimensional array in a function’s parameter list
• void afunction(int amatrix[ ][10]);
– Because arrays are referenced through pointers, there are multiple ways to
declare and access 2+ dimensional arrays
• This will be more relevant when dealing with an array of strings (which is a 2-D
array)
int a[10][20];
int *a[10];
int **a;
*a[4] –first element of 5th array element
*a[9] –first element of 10th array element
**a –first element of a[0]
int *a[3]; // array of 3 pointers
int x[2] = {1, 2};
int y[3] = {3, 4, 5};
int z[4] = {6, 7, 8, 9};
*a = &x[0]; // a[0] points to x[0]
*(a+1) = &y[0]; // a[1] points to y[0]
*(a+2) = &z[0]; // a[2] points to z[0]
// array a is a jagged array, it is not
// rectangular, or of equal dimensions
12. Pointers to Pointers
• As indicated in the last slide, we can have an array
of arrays which is really an array of pointers or
pointers to pointers
– We may wish to use pointers to pointers outside of
arrays as well, although it is more common that
pointers to pointers represent array of pointers
– Consider the following:
int a;
int *p;
int **q;
a = 10;
p = &a;
q = &p;
printf(“%d”, **q); // outputs 10
We dereference our pointer p with *p but we dereference
our pointer to a pointer q with **q
*q is actually p, so **q is a
13. Arrays of Strings Implementation
• We could implement an array of strings as a 2-D array of chars
– char array[10][10];
• This has two disadvantages
– All strings will be 10 chars long
– Requires 2 nested for-loops for most operations such as string comparison
or string copying, which can become complicated
• Instead, we will implement our array of strings as an array of
pointers
– char *array[10];
• Each pointer points to one string
– Follow the string through the pointer
– Go to the next string using a for-loop
– Because strcpy, strcmp, strlen all expect pointers, we can use these by
passing an array element (since each array element is a pointer to a string)
14. Example
• Notice that if we had used char x[ ][ ] = {…}; then the storage
space would have been 4 strings of length 23 (the length of the
longest string) or 92 bytes instead of 42 bytes as it is above
char *x[ ] = {"hello", "goodbye", "so long", "thanks for all the fish"};
// our array of strings x is a set of 4 pointers
char *y; // let y be a pointer to a char so it can be used to move through a single string
int i;
for(i=0;i<4;i++) // iterate for each string in x
{
y = x[i]; // x[i] is an array, x is really a pointer, so this sets y to x’s starting addr.
while(*y!='0') // while the thing y points to is not the end of a string
{
printf("%c", *y); // print what y points to
y++; // and go on to the next char in x
}
printf("n"); // separate strings in output with n
}
15. Passing Arrays
• When an array is passed to
a function, what is being
passed is a pointer to the
array
– In the formal parameter list,
you can either specify the
parameter as an array or a
pointer
• Because you can compile
functions separately, the
compiler must be able to
“know” about an array being
passed in to a function, so you
must specify all (or most) of
the definition:
– The type and all dimensions
except for the first
int array[100];
…
afunction(array);
…
void afunction(int *a) {…}
or
void afunction(int a[ ]) {…}
int array[5][10][15];
…
afunction(array);
…
void afunction(int a[ ][10][15]) {…} or
void afunction(int *a[10][15]) {…} or
void afunction(int a[5][10][15]) {…} or
void afunction(int **a[15]) {…} etc
16. Some Additional Comments
• In functions, do not do return p; where p is a pointer
– Recall local variables are deallocated when the function ends
• so whatever p is pointing to will no longer be available
• but if you return the pointer, then you still are pointing at that memory
location even though you no longer know what is there
• We can declare a pointer to point to a void type, which
means that the pointer can point to any type
– However, this does require a cast before the pointer can be
assigned
• int x; float y; void *p; // p can point to either x or y
• p = (int *) &x; // p can point to int x once the address is cast
• p = (float *) &y; // or p can point to float y
• Pointers that don’t currently point to anything have the
special value NULL and can be tested as (p = = NULL)
or (!p), and (p != NULL) or (p)