This document provides an overview of programming in C and functions. It discusses implementing modular approaches using functions, parameters and return values of functions, passing arrays and command line arguments to functions, and using library functions for string manipulation and converting data types. Examples and practice problems are provided relating to defining and calling functions, passing arguments by value and reference, and using standard string and numeric conversion functions. The overall aim is to teach how to work with functions and data types in C programming.
Programming is hard. Programming correct C and C++ is particularly hard. Indeed, both in C and certainly in C++, it is uncommon to see a screenful containing only well defined and conforming code.Why do professional programmers write code like this? Because most programmers do not have a deep understanding of the language they are using.While they sometimes know that certain things are undefined or unspecified, they often do not know why it is so. In these slides we will study small code snippets in C and C++, and use them to discuss the fundamental building blocks, limitations and underlying design philosophies of these wonderful but dangerous programming languages.
This content has a CC license. Feel free to use it for whatever you want. You may download the original PDF file from: http://www.pvv.org/~oma/DeepC_slides_oct2012.pdf
Programming is hard. Programming correct C and C++ is particularly hard. Indeed, both in C and certainly in C++, it is uncommon to see a screenful containing only well defined and conforming code.Why do professional programmers write code like this? Because most programmers do not have a deep understanding of the language they are using.While they sometimes know that certain things are undefined or unspecified, they often do not know why it is so. In these slides we will study small code snippets in C and C++, and use them to discuss the fundamental building blocks, limitations and underlying design philosophies of these wonderful but dangerous programming languages.
This content has a CC license. Feel free to use it for whatever you want. You may download the original PDF file from: http://www.pvv.org/~oma/DeepC_slides_oct2012.pdf
This presentation is part of training session delivered during Train The Trainer (TOT) program on Embedded Software Engineer job role supported by ESSCI.
This presentation is part of training session delivered during Train The Trainer (TOT) program on Embedded Software Engineer job role supported by ESSCI.
Programming Fundamentals Functions in C and typesimtiazalijoono
Programming Fundamentals
Functions in C
Lecture Outline
• Functions
• Function declaration
• Function call
• Function definition
– Passing arguments to function
1) Passing constants
2) Passing variables
– Pass by value
– Returning values from functions
• Preprocessor directives
• Local and external variables
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Thesis Statement for students diagnonsed withADHD.ppt
C programming session 08
1. Slide 1 of 44Ver. 1.0
Programming in C
In this session, you will learn to:
Implement modular approach in C programs
Use library functions for string manipulation
Work with data storage types
Objectives
2. Slide 2 of 44Ver. 1.0
Programming in C
Implementing Modular Approach in C Programs
Functions are the building blocks of C.
Every C program must consist of at least one function,
main().
The main() function is the entry point of a C program.
3. Slide 3 of 44Ver. 1.0
Programming in C
Advantages of Functions
Functions:
Allow reusability of code and structuring of programs.
Provide programmers a convenient way of designing
programs.
4. Slide 4 of 44Ver. 1.0
Programming in C
Parameters of Functions
A parameter:
Is the data that the function must receive when called from
another function.
May or may not be present in a function.
Of a user-defined function is declared outside the {} of that
function.
5. Slide 5 of 44Ver. 1.0
Programming in C
Practice: 5.1
1. From the following program, identify the functions invoked
from main(), and state which functions have parameters.
Also state the parameters.
Microsoft Office
Word 97 - 2003 Document
6. Slide 6 of 44Ver. 1.0
Programming in C
Practice: 5.1 (Contd.)
Solution:
1. The standard functions used in this program within main() are
as follows:
scanf() – parameters are format of input, and pointers to the
variable(s) in which the input must be stored
fflush() – parameter is stdin
The user-defined functions are:
output() – no parameters
calc() – one parameter, g, an int type data
7. Slide 7 of 44Ver. 1.0
Programming in C
Invoking Functions
Functions that have parameters are invoked in one of the
following ways:
Call by value: In call by value, the called function cannot refer
to the variables of the caller function directly, but creates its
own copy of the values in different variables.
Call by reference: In call by reference, the called function
should be able to refer to the variables of the caller function
directly, and does not create its own copy of the values in
different variables. It is possible only if the addresses of the
variables are passed as parameters to a function.
8. Slide 8 of 44Ver. 1.0
Programming in C
Passing Arrays to Functions
Arrays are inherently passed to functions through call by
reference method.
An array can be passed to a function in the following way:
Function name (array name);
9. Slide 9 of 44Ver. 1.0
Programming in C
Practice: 5.2
1. If the variable avar is passed to a function by a call by
reference, can the value of the variable avar be modified in
the called function? Give reasons for your answer.
2. State whether True or False:
When an array is passed to a function, the array elements
are copied into the parameter of the function.
3. Consider the program code given in the following file.
Microsoft Office
Word 97 - 2003 Document
10. Slide 10 of 44Ver. 1.0
Programming in C
Practice: 5.2 (Contd.)
Based on the code, answer the following questions:
a. The function (max() / min()) is invoked by a call by value.
b. The function (max() / min()) is invoked by a call by reference.
c. After the function max() is executed, where does the control go to:
i. The min() function.
ii. The first line of the main() function.
iii. The first line of the main() following the line on which max() was invoked.
d. After execution of the function min(), program execution:
i. Stops without returning to main().
ii. Goes back to the main() function.
e. If the values of i and j were to be printed after the function max() and
again after the function min(), what values would be displayed?
11. Slide 11 of 44Ver. 1.0
Programming in C
Practice: 5.2 (Contd.)
4. Write a program that calls a function called power(m,n),
which displays the nth power of the integer m (m and n are
parameters). The function must be invoked by a call by
reference.
12. Slide 12 of 44Ver. 1.0
Programming in C
Practice: 5.2 (Contd.)
Solution:
1. Yes, because the addresses of the variables are passed in by
using call by reference, the memory locations of the variables
are known to the function. Using pointers to the variables, their
values can be modified.
2. False. Values of variables are copied into the parameters only
in the case of a call by value.
3. a. max()
b. min()
c. iii
d. ii
e. After max() is executed, the values of i and j printed out
would be the same as those entered during execution. After
min() is executed, the value of i would still be the same, but
j would increase by 5 (since b is a pointer to the variable j).
13. Slide 13 of 44Ver. 1.0
Programming in C
4.main() {
int x, y;
printf(“Enter Number: ”);
scanf(“%d”, &x);
fflush(stdin);
printf(“Enter power raise to : “);
scanf(“%d”, &y);
fflush(stdin);
power(&x, &y); }
power(m,n)
int *m, *n; /* power is pointed to by n,
value is pointed to by m */
{ int i=1,val=1;
while(i++<= *n)
val = val ** m;
printf(“%d the power of %d is %dn”, *n,*m,
val);}
Practice: 5.2 (Contd.)
14. Slide 14 of 44Ver. 1.0
Programming in C
Returning Values from a Function
A function can return a value to the caller function.
The return statement is used to send back a value to the
caller function.
The return statement also transfers control back to calling
function.
The default return value is int type.
The return statement can return only one value.
The syntax for the return statement is:
return[expression]
A function can also return an array. This could be done by:
return [array name]
15. Slide 15 of 44Ver. 1.0
Programming in C
Practice: 5.3
1. Point out the error(s), if any, in the functions given in the
following file:
2. The following program should calculate the square of any
float value, using a function called square(). The float value
is an input to the program. The program is incomplete. Put
in the appropriate statements in the program given in the
following file:
Microsoft Word
Document
Microsoft Word
Document
16. Slide 16 of 44Ver. 1.0
Programming in C
Practice: 5.3 (Contd.)
3. The function, makeint(), was coded to convert any
number entered into a char array to integer type. The
function takes the string as parameter and returns the
value, as given in the following file:
Microsoft Word
Document
17. Slide 17 of 44Ver. 1.0
Programming in C
Practice: 5.3 (Contd.)
Solution:
Microsoft Word
Document
18. Slide 18 of 44Ver. 1.0
Programming in C
Command-Line Arguments
Command-line arguments:
Are the parameters that the main() function can receive from
the command line.
Are passed as information from the OS prompt to a program.
The main() function has 2 arguments, argc and argv.
The format of the main() function with parameters is as
follows:
main(argc, argv)
int argc;
char *argv[];
{
:
}
Here, argc is integer and argv is a character array of
unlimited size (hence [ ] in the declaration).
19. Slide 19 of 44Ver. 1.0
Programming in C
Practice: 5.4
1. Given that a C program called temp is executed by the
following command:
temp start 6
match the following:
a. value of argc 1. points to array "6"
b. argv [0] 2. points to arrm/ "start"
c. argv [1] 3. 3
d. argv[2] 4. points to array "temp"
2. Modify the program upper so that it first checks the number
of arguments entered on the command line. The program
should display an error message if no arguments have been
entered and also allow conversion of as many strings to
upper-case as have been specified as arguments on the
command line.
20. Slide 20 of 44Ver. 1.0
Programming in C
Practice: 5.4 (Contd.)
3. Consider the following program to calculate the sum of 2
integers specified on the command line:
main (argc, argv)
int argc;
char *argv [ ];{
sum (argv [1], argv [2]);
}
sum (num1, num2)
int numl, num2;{
return numl + num2;
}
The program has some logical errors. Point out the errors and
correct the code.
21. Slide 21 of 44Ver. 1.0
Programming in C
Practice: 5.4 (Contd.)
Solution:
Microsoft Word
Document
22. Slide 22 of 44Ver. 1.0
Programming in C
Using Library Functions for String Manipulation
Library functions:
Are also known as built-in functions.
Can be used by including the concerned header files.
23. Slide 23 of 44Ver. 1.0
Programming in C
Standard String-Handling Functions
Some of the standard string-handling functions are:
strcmp(): Compares 2 strings (its parameters) character by
character (ASCII comparison).
strcpy(): Copies the second string to the first string named
in the strcpy() parameters.
strcat(): Appends the second string passed at the end of
the first string passed to it .
strlen(): Returns the number of characters in the string
passed to it.
24. Slide 24 of 44Ver. 1.0
Programming in C
Practice: 5.5
1. What will the following function call return?
x = strcmp(“Cada”, “CADA”);
What should the declaration of x be?
2. Assume that array contains the string 846*.
What will array contain when the following statement is executed?
strcat(array,”>”);
3. State whether True or False:
The following statement returns a value of 4 to x.
x = strlen ("abc");
25. Slide 25 of 44Ver. 1.0
Programming in C
Practice: 5.5 (Contd.)
Solution:
1. Value returned - 32
Declaration - int x;
2. 846*>
3. False
26. Slide 26 of 44Ver. 1.0
Programming in C
String to Numeric Conversion Functions
Conversion functions:
Are available as a part of the standard library.
Are used to convert one data type into another.
The following functions are used to convert a string to a
numeric value:
atoi(): Returns the int type value of a string passed to it
and the value 0 in the case the string does not begin with a
digit.
atof(): Returns the double type value of a string passed to it
and the value 0 in the case the string does not begin with a
digit or a decimal point.
27. Slide 27 of 44Ver. 1.0
Programming in C
Practice: 5.6
1. What value will the variable val contain in each of the
following situations?
a. val = atoi ("A345"); /* val is int type */
b. val = atof ("345A"); /* val is double type */
28. Slide 28 of 44Ver. 1.0
Programming in C
Practice: 5.6 (Contd.)
Solution:
1. a. 0
b. 345.000000
29. Slide 29 of 44Ver. 1.0
Programming in C
Functions for Formatting Data in Memory
The formatting functions are available as a part of the
standard library.
The following functions are used to format data in memory:
sprintf():
Writes to a variable in the memory and stores the data in different
variables specified.
Are used for transferring data between variables in a specific
format.
Has the following syntax:
sprintf(string, format-specification, data, ….);
sscanf():
Performs formatted input from a string.
Has the following syntax:
sscanf(string, format-specification, data, ….);
30. Slide 30 of 44Ver. 1.0
Programming in C
Practice: 5.7
1. What data is assigned to the variable string by each of the
following?
a. sprintf(string,"%04d%3.2f%2s",21,4.576, "Hi“);
b. sprintf (string, "%10s", "ABC");
c. sscanf ("0987APZ", "%4d%s", &num, string);
1. What is the error, if any, in the instructions given below
against each purpose? Give the correct instruction in case
of an error.
Purpose Instruction
Accept a name from keyboard printf(“%s”, name);
Format the contents of variables
i_num(int) and f_num(float), and store
them into a character array called string.
printf (string,"%d%f, i_num,f_num)
31. Slide 31 of 44Ver. 1.0
Programming in C
Practice: 5.7 (Contd.)
Solution:
Microsoft Word
Document
32. Slide 32 of 44Ver. 1.0
Programming in C
Working with Data Storage Types
C language provides the following data storage types:
auto: Variables of this type retain their value only as long as
the function is in the stage of execution.
static: Variables of this type retain its value even after the
function to which it belongs has been executed.
extern: Variables of this type are declared at the start of the
program and can be accessed from any function.
33. Slide 33 of 44Ver. 1.0
Programming in C
Practice: 5.8
1. Given the following declarations:
float area;
static float val;
auto char number;
State which variable(s) will be:
a. Created each tune the function is invoked.
b. Created only once.
2. A numeric array has to store 4 values - 2.5, 6,3, 7.0 and 8.0.
This array is to be declared and used in a function called
compute(). Which of the following is/are correct
declarations of this array?
a. static int values[4] = {2.5,6.3,7.0,8.0};
b. auto float values[4] = {2.5,6.3,7.0,8.0 };
c. float values [4]= {2.5,6.3,7.0,8.0};
d. static float values [4] = {2.5,6.3,7.0,8.0};
34. Slide 34 of 44Ver. 1.0
Programming in C
Practice: 5.8 (Contd.)
Solution:
1. a. area, number
b. val
2. (a) Is invalid because the array should be float or double type.
(b) Is invalid because it is declared as auto type.
(c) Is invalid because it is declared as auto type.
(d) Is correct.
.
35. Slide 35 of 44Ver. 1.0
Programming in C
Practice: 5.9
1. If the variable val is declared as global in the program B,
just illustrated, how would program A be modified? Give the
appropriate declarations required in both programs.
2. Consider the following 2 program files:
Program A
float x;
calc() {
int i;
: } printout()
{ static char z;
: }
Program B
char numarray[5];
main() {
char c ;
: }
36. Slide 36 of 44Ver. 1.0
Programming in C
Practice: 5.9 (Contd.)
Based on this code, answer the following:
a. The variable z can be accessed in the function(s)
____________________.
b. The variable(s) that can be accessed from functions of both program
files is/are ___________.
c. Slate whether True or False:
The variable i can be used in the function printout().
d. Memory for variable z is reserved each time the function printout()
is invoked. State whether true or false.
e. If the function printout() has to access the variable x, does x have
to be declared within the function printout()?
If so, give the declaration.
f. The auto variable(s) in these programs is/are _________________.
37. Slide 37 of 44Ver. 1.0
Programming in C
Practice: 5.9 (Contd.)
Solution:
1. In program B, val would be declared as follows:
int val;
calc(){
:}
In program A, the declaration would be as follows:
main()
{ extern int val;
:}
2. a. printout() only (Since it is declared within the function
printout() and hence is not global)
x and numarray (if proper extern statements are coded).
b. False (Since it is declared within the function calc(), and
hence it is not global)
38. Slide 38 of 44Ver. 1.0
Programming in C
Practice: 5.9 (Contd.)
c. False (Since z is a static variable, it is created only
once – the function printout() is invoked.)
d. No (Since x is declared as global in program A, and
printout() is defined in the same program file. However,
declaring it as extern while within printout() is wrong.)
e. The variable i defined in calc() and the variable c defined
in main().
39. Slide 39 of 44Ver. 1.0
Programming in C
Practice: 5.10
1. The following file contains a C program called remdigit.c
and a list of errors in the program indicated by the compiler.
Go through the error list and correct the program. Since the
C compiler does not always give very meaningful error
messages, go through the program given in the following
file carefully.
Microsoft Office
Word 97 - 2003 Document
40. Slide 40 of 44Ver. 1.0
Programming in C
Practice: 5.10 (Contd.)
2. Write a program to display all the positions at which a
character occurs in a string. Both the character to be
located and the string to be searched should be passed to a
function called nextpos (findchar, searchstr).
Each time the function locates the diameter, it should pass
back the position.
After searching the entire string, the function should return
the value -1.
41. Slide 41 of 44Ver. 1.0
Programming in C
Practice: 5.10 (Contd.)
Solution:
Work out your answers. A discussion on these follows in the
Classroom.
42. Slide 42 of 44Ver. 1.0
Programming in C
Summary
In this session, you learned that:
Functions provide advantages of reusability and structuring of
programs.
A parameter of a function is the data that the function must
receive when called or invoked from another function.
Functions that have parameters are invoked in one of the
following two ways:
Call by value
Call by reference
Call by value means that the called function creates its own
copy of the values in different variables.
Call by reference means that the called function should be able
to refer to the variables of the caller function directly, and does
not create its own copy of the values in different variables.
43. Slide 43 of 44Ver. 1.0
Programming in C
Summary (Contd.)
Arrays are passed to functions by the call by reference
method.
Functions can return values by using the return statement.
The main() function can have parameters, argc and argv.
argc is integer type while argv is a string.
The information that is passed to a program from the OS
prompt is known as command-line arguments.
Some of the standard string-handling functions are:
strcmp(): Compares two strings.
strcpy(): Copies the second string to the first string.
strcat(): Appends the second string passed at the end of the
first string passed as parameters.
strlen(): Returns the number of characters in the string
passed as a parameter.
44. Slide 44 of 44Ver. 1.0
Programming in C
Summary (Contd.)
atoi(): Returns the int type value of a string passed to it.
aof(): Returns the double type value of a string passed to it.
The following functions are used to format data in memory:
sprintf()
sscanf()
C language provides the following data storage types:
auto: Variables of this type retain their value only as long as the
function is in the stage of execution.
static: Variables of this type retain its value even after the
function to which it belongs has been executed.
extern: Variables of this type are declared at the start of the
program and can be accessed from any function.
Editor's Notes
Begin the session by explaining the objectives of the session.
Give an example where you need to use a function for reusability.
Tell the students that a parameter is a means by which functions pass information.
Use this slide to test the student’s understanding on parameters.
Tell the students that calling a function is termed as invoking a function. A function is invoked or called by writing the function name with parameters, if any. Also discuss actual parameters and formal parameters. What is implemented in C is not a true call by reference. A call by reference actually involves providing an alias for the original variable being referenced. There should be no difference in the way the original variable and the referencing variable is used (even in the syntax). What happens in C is that the address of the variable is passed. This address is received into a pointer and the pointer is dereferenced. Here a local variable (the pointer) is created in the called function. In a true call by reference , a variable is not created.
Use this slide to test the student’s understanding on call by value and call by reference.
As parameters are used to pass the required information to the called function, similarly, the return statement is used to pass the result back to the calling function.
Use this slide to test the student’s understanding on returning values from a function.
Explain command-line arguments to the students. Give the example of the copy command in MS DOS. Tell the students that copy is the command and the name of the source and the target file are the arguments to the copy command. The command-line arguments are separated by a space.
Use this slide to test the student’s understanding on command-line arguments.
Tell the students that if they want to ignore case while comparing two strings, they can use the strcmpi() function.
Use this slide to test the student’s understanding on string-handling functions.
Use this slide to test the student’s understanding on string to numeric conversion functions.
Use this slide to test the student’s understanding on sscanf() and sscanf() functions.
Use this slide to test the student’s understanding on data storage types .
Use this slide to test the student’s understanding on data storage types .
Use this and the next 2 slides to summarize the session.