This document provides an overview of references and pointers in C++. It discusses that references act as aliases to existing variables while pointers store the address of a variable in memory. It also covers dynamic memory allocation using pointers, the relationship between arrays and pointers, using pointers and const, and passing pointers to functions. Potential issues with pointers like uninitialized pointers and dangling pointers are also mentioned.
A pointer is a variable whose value is the address of another variable, i.e., direct address of the memory location. Like any variable or constant, you must declare a pointer before you can use it to store any variable address.
There are few important operations, which we will do with the help of pointers very frequently. (a) we define a pointer variable (b) assign the address of a variable to a pointer and (c) finally access the value at the address available in the pointer variable. This is done by using unary operator * that returns the value of the variable located at the address specified by its operand.
In computer science, a pointer is a programming language object, whose value refers to (or "points to") another value stored elsewhere in the computer memory using its memory address. A pointer references a location in memory, and obtaining the value stored at that location is known as dereferencing the pointer.
A pointer is a variable whose value is the address of another variable, i.e., direct address of the memory location. Like any variable or constant, you must declare a pointer before you can use it to store any variable address.
There are few important operations, which we will do with the help of pointers very frequently. (a) we define a pointer variable (b) assign the address of a variable to a pointer and (c) finally access the value at the address available in the pointer variable. This is done by using unary operator * that returns the value of the variable located at the address specified by its operand.
In computer science, a pointer is a programming language object, whose value refers to (or "points to") another value stored elsewhere in the computer memory using its memory address. A pointer references a location in memory, and obtaining the value stored at that location is known as dereferencing the pointer.
1. Introduction to Pointers:
- Pointers are variables that store memory addresses. They provide a way to directly manipulate memory, enabling efficient and flexible programming.
2. Pointer to Pointer:
- A pointer that holds the address of another pointer. Useful in scenarios where multiple levels of indirection are required.
3. Null Pointer, Generic Pointer, and Dangling Pointer:
- Discusses the concepts of null pointers (pointers with no valid address), generic pointers (void pointers), and dangling pointers (pointers pointing to released memory).
4. Passing an Array to a Function:
- Explains how to pass arrays to functions, emphasizing the use of pointers to efficiently work with arrays in functions.
5. Returning an Array from Function:
- Explores the technique of returning arrays from functions, often involving the use of pointers to manage memory.
6. Array of Pointers:
- Describes the concept of an array where each element is a pointer, enabling the creation of dynamic data structures.
7. Pointers and 1D Array:
- Examines the relationship between pointers and one-dimensional arrays, highlighting how pointers can be used for array manipulation.
8. Pointers and 2D Array:
- Discusses the use of pointers in managing two-dimensional arrays, which involves handling rows and columns efficiently.
9. Using Pointers for String Manipulation:
- Illustrates how pointers are employed for efficient manipulation of strings, emphasizing dynamic memory allocation for flexible string handling.
10. Two-dimensional Array of Strings:
- Explores the combination of pointers and arrays to handle two-dimensional arrays of strings.
11. Array of Pointers to String:
- Focuses on the concept of an array where each element is a pointer to a string, allowing for dynamic string management.
Pointers are among C’s most powerful, yet most difficult concepts to master. Some tasks like dynamic memory allocation done only by using pointers. So it is essential to learn pointers.
Pointers are a type of variable, just like int, double, etc., except instead of storing a value, they store a memory address of another variable.
Pointers in C language is a variable that stores/points the address of another variable. A Pointer in C is used to allocate memory dynamically i.e. at run time.
general use of pointer
what is pointer in c language
uses is pointer in c language
representation of pointer in c language
syantax of pointer in c language
program of pointer in c language
(4) cpp automatic arrays_pointers_c-stringsNico Ludwig
Check out these exercises: http://de.slideshare.net/nicolayludwig/4-cpp-automatic-arrayspointerscstringsexercises-38510502
- Pointers: Call by Value versus Call by Reference
- Automatic Arrays
- Arrays and Pointer Decay
- Pointers to Pointers
- C-strings as Arrays and their Memory Representation
- Basic C-string Functions
At the end of this lecture students should be able to;
Define the C pointers and its usage in computer programming.
Describe pointer declaration and initialization.
Apply C pointers for expressions.
Experiment on pointer operations.
Identify NULL pointer concept.
Experiment on pointer to pointer, pointer arrays, arrays with pointers and functions with pointers.
Apply taught concepts for writing programs.
1. Introduction to Pointers:
- Pointers are variables that store memory addresses. They provide a way to directly manipulate memory, enabling efficient and flexible programming.
2. Pointer to Pointer:
- A pointer that holds the address of another pointer. Useful in scenarios where multiple levels of indirection are required.
3. Null Pointer, Generic Pointer, and Dangling Pointer:
- Discusses the concepts of null pointers (pointers with no valid address), generic pointers (void pointers), and dangling pointers (pointers pointing to released memory).
4. Passing an Array to a Function:
- Explains how to pass arrays to functions, emphasizing the use of pointers to efficiently work with arrays in functions.
5. Returning an Array from Function:
- Explores the technique of returning arrays from functions, often involving the use of pointers to manage memory.
6. Array of Pointers:
- Describes the concept of an array where each element is a pointer, enabling the creation of dynamic data structures.
7. Pointers and 1D Array:
- Examines the relationship between pointers and one-dimensional arrays, highlighting how pointers can be used for array manipulation.
8. Pointers and 2D Array:
- Discusses the use of pointers in managing two-dimensional arrays, which involves handling rows and columns efficiently.
9. Using Pointers for String Manipulation:
- Illustrates how pointers are employed for efficient manipulation of strings, emphasizing dynamic memory allocation for flexible string handling.
10. Two-dimensional Array of Strings:
- Explores the combination of pointers and arrays to handle two-dimensional arrays of strings.
11. Array of Pointers to String:
- Focuses on the concept of an array where each element is a pointer to a string, allowing for dynamic string management.
Pointers are among C’s most powerful, yet most difficult concepts to master. Some tasks like dynamic memory allocation done only by using pointers. So it is essential to learn pointers.
Pointers are a type of variable, just like int, double, etc., except instead of storing a value, they store a memory address of another variable.
Pointers in C language is a variable that stores/points the address of another variable. A Pointer in C is used to allocate memory dynamically i.e. at run time.
general use of pointer
what is pointer in c language
uses is pointer in c language
representation of pointer in c language
syantax of pointer in c language
program of pointer in c language
(4) cpp automatic arrays_pointers_c-stringsNico Ludwig
Check out these exercises: http://de.slideshare.net/nicolayludwig/4-cpp-automatic-arrayspointerscstringsexercises-38510502
- Pointers: Call by Value versus Call by Reference
- Automatic Arrays
- Arrays and Pointer Decay
- Pointers to Pointers
- C-strings as Arrays and their Memory Representation
- Basic C-string Functions
At the end of this lecture students should be able to;
Define the C pointers and its usage in computer programming.
Describe pointer declaration and initialization.
Apply C pointers for expressions.
Experiment on pointer operations.
Identify NULL pointer concept.
Experiment on pointer to pointer, pointer arrays, arrays with pointers and functions with pointers.
Apply taught concepts for writing programs.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
3. OVERVIEW OF REFERENCES AND POINTERS
Often need to refer to another object
– Without making a copy of the object itself
– Also known as “aliasing”
Two ways to do this
– Directly, via a reference
o • Acts as an alias for the object
o • User interacts with reference as if it were the object itself
– Indirectly, via a pointer
o • Gives the address (in memory) of the object
o • Requires the user to do extra work: dereferencing
5. WHAT IS A REFERENCES
Reference is an alternative name for an existing variable (alias).
• A variable holding an address of what it “refers to” in memory
• But with a nicer interface
– An alias to the object
– Hides indirection from programmer
• Must be typed
– Checked by compiler
– Again can only refer to the type to which it can point
int &r = i; // can only refer to int
• Must always refer to something
– Must be initialized, cannot be changed
– More restricted than Java references
6. WHAT IS A POINTER
Pointers is simply a variable that maintain as a value the address of another location in
memory.
A variable holding an address of what it “points to” in memory
• Can be untyped
void * v; // can point to any type
• However, usually they’re typed
– Checked by compiler
– Can only be assigned addresses of variables of the type to which it can point
int * p; // can only point to int
• Addresses: garbage, something, nothing
– When created: int * p = i; vs. int * q;
q = 0; // now it points to nothing
p = NULL; // not portable, use nullptr instead
7. WHAT IS A POINTER
Pointers is simply a variable that maintain as a value the address of another location in
memory.
A variable holding an address of what it “points to” in memory
• Can be untyped
void * v; // can point to any type
• However, usually they’re typed
– Checked by compiler
– Can only be assigned addresses of variables of the type to which it can point
int * p; // can only point to int
• Addresses: garbage, something, nothing
– When created: int * p = i; vs. int * q;
q = 0; // now it points to nothing
p = NULL; // not portable, use nullptr instead
8. REFERENCE AND POINTER VARIABLES
Variable and object values are stored in particular locations in the computer’s memory.
Reference and pointer variables store the memory location of other variables.
Pointers are found in C. References are a C++ variation that makes pointers easier and safer to
use.
string hello = "Hello";
string *hello_ptr = &hello;
string &hello_ref = hello;
The object hello
occupies some
computer memory.
The asterisk indicates that hello_ptr is a
pointer to a string. hello_ptr variable is
assigned the memory address of object hello
which is accessed with the “&” syntax.
The & here indicates that hello_ref is a reference to a
string. The hello_ref variable is assigned the memory
address of object hello automatically.
REFERENCE AND POINTER VARIABLES
9. Difference between reference and pointers
A reference can never be null; it must always refer to a legitimate object.
Once established, a reference can never be changed to make it point to a different object.
A reference does not require any explicit mechanism to dereference the memory address and
access the actual data value.
REFERENCE AND POINTER VARIABLES
10. DYNAMIC MEMORY ALLOCATION
Dynamic memory allocation is the process of allocating and freeing memory during the execution
of a program.
It is useful when the memory needs of a program are not known in advance, or when they change
during the program’s lifetime.
It differs from static memory allocation, which is done at compile time and cannot be changed
afterwards.
11. DYNAMIC MEMORY ALLOCATION
Suppose we want to create an array of integers with a size that is determined by the user’s input.
We cannot use a regular array declaration, because the size must be a constant expression. Instead,
we can use dynamic memory allocation with pointers:
int *arr; // declare a pointer to int
int n; // declare an int variable to store the size
cout << "Enter the size of the array: ";
cin >> n; // read the size from the user
arr = new int[n]; // allocate memory for n elements
of type int and assign the address to arr
// now we can use arr as a regular array, for
example:
for (int i = 0; i < n; i++) {
arr[i] = i + 1; // assign some values to the array
elements
}
for (int i = 0; i < n; i++) {
cout << arr[i] << " "; // print the array elements
}
pointer = new type; // allocate memory for one
element of type type and assign the address to
pointer
pointer = new type[size]; // allocate memory for
an array of size elements of type type and
assign the address to pointer
delete pointer; // free the memory pointed by pointer
(one element)
delete[] pointer; // free the memory pointed by pointer
(an array)
12. DYNAMIC MEMORY ALLOCATION
Advantages: Some advantages of using dynamic memory allocation are:
It allows us to create data structures with variable sizes, such as linked lists, trees, graphs, etc.
It can improve the efficiency and performance of a program by avoiding unused or wasted
memory.
It can avoid memory overflow errors by allocating memory only when needed.
Disadvantages: Some disadvantages of using dynamic memory allocation are:
It adds complexity and overhead to a program, as we need to manage the memory manually
and check for errors.
It can cause memory leaks or errors if we forget to free the memory or use invalid pointers.
It can fragment the memory heap, making it harder to find contiguous blocks of memory.
13. RELATIONSHIP BETWEEN ARRAYS AND POINTERS
The value of an array name is the address of the first element in the array
The value of a pointer variable is an address
If the pointer points to the same data type as the array element then the pointer and
array name can be used interchangeably (almost).
14. POINTERS AND CONST IN C++
Pointers are variables that store the address of another variable or object in memory.
const is a keyword that indicates that a variable or object is constant, meaning its value cannot be
changed after initialization.
Pointers and const can be used together in C++ to create different types of pointers that have
different levels of constness.
Suppose we have two variables, a and b, of type int, and we want to create pointers to them. We
can use the following declarations:
15. POINTERS AND CONST IN C++
Now we can use these pointers to access or modify the values of a and b, depending on the type of
pointer. For example:
16. PASSING POINTERS TO FUNCTIONS
Pass-by-reference with pointer parameters
We can use pointers and the dereference operator to achieve pass-by- reference
The function parameter is a pointer
The actual parameter can be a pointer or address of a variable
void double_data(int *int_ptr);
void double_data(int *int_ptr) {
*int_ptr *= 2;
}
17. POTENTIAL POINTER PITFALLS
Uninitialized pointers
Dangling Pointers
Not checking if new failed to allocate memory
Leaking memory