The document provides an overview of C functions, covering their definition, types, and utility in programming. It details the concepts of call by value and call by reference, along with examples demonstrating their usage. Additionally, the document discusses recursion in C programming, illustrating its principles and applications.

1. FUNCTION IN CMS. LOTHE SAVITAA.
DEPT OF COMPUTER SCIENCE
VASANTRAO NAIK MAHAVIDYALAYA, AURANGABAD..

2. TO STUDY…
 Introduction, types of functions.
 Defining functions, Arguments,
 Function prototype, actual parameters and formal
parameters,
 Calling function, Returning function results,
 Call by value, Recursion.
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3. INTRODUCTION
 C functions are basic building blocks in a program.
 All C programs are written using functions to
improve re-usability, understandability and to keep
track on them.
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4. WHAT IS FUNCTION?
 A large C program is divided into basic building blocks
called C function.
 C function contains set of instructions enclosed by “{ }”
which performs specific operation in a C program.
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FUNCTION IN C PROGRAMMING

5. USES OF C FUNCTIONS:
C functions are used to avoid rewriting same logic/code again and again in a
program.
There is no limit in calling C functions to make use of same functionality
wherever required.
We can call functions any number of times in a program and from any place in
a program.
A large C program can easily be tracked when it is divided into functions.
The core concept of C functions are, re-usability, dividing a big task into small
pieces to achieve the functionality and to improve understandability of very
large C programs. 5
FUNCTION IN C PROGRAMMING

6. FUNCTION
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7. PROGRAM SHOWING FUNCTION IN C
#include<stdio.h>
float square ( float x ); // function prototype, also called function declaration
int main( )
{
float m, n ;
printf ( "n Enter some number for finding square n");
scanf ( "%f", &m ) ;
n = square ( m ) ; // function call
printf ( "nSquare of the given number %f is %f",m,n );
}
float square ( float x ) // function definition
{
float p ;
p = x * x ;
return ( p ) ;
}
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8. HOW TO CALL C FUNCTIONS IN A
PROGRAM?
Call by value
Call by reference
THERE ARE
TWO WAYS
THAT A C
FUNCTION CAN
BE CALLED
FROM A
PROGRAM.
THEY ARE,
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9. CALL BY VALUE
In call by value method, the value of the variable is passed to the
function as parameter.
The value of the actual parameter can not be modified by formal
parameter.
Different Memory is allocated for both actual and formal
parameters. Because, value of actual parameter is copied to
formal parameter.
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10. Actual parameter – This is the argument which
is used in function call.
Formal parameter – This is the argument
which is used in function definition
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11. PROGRAM FOR CALL BY VALUE
#include<stdio.h>
void swap(int a, int b); // function prototype, also called function declaration
int main()
{
int m = 22, n = 44;
printf(" values before swap m = %d nand n = %d", m, n); // calling swap function by value
swap(m, n);
}
void swap(int a, int b)
{
int tmp;
tmp = a;
a = b;
b = tmp;
printf(" nvalues after swap m = %dn and n = %d", a, b);
}
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12. CALL BY REFERENCE
In call by reference method, the address of the variable is
passed to the function as parameter.
The value of the actual parameter can be modified by
formal parameter.
Same memory is used for both actual and formal
parameters since only address is used by both
parameters.
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13. EXAMPLE SHOWING CALL BY REFERENCE
#include<stdio.h>
void swap(int *a, int *b); // function prototype, also called function declaration
int main()
{ int m = 22, n = 44;
printf("values before swap m = %d n and n = %d",m,n); // calling swap function by
reference
swap(&m, &n);
}
void swap(int *a, int *b)
{
int tmp;
tmp = *a;
*a = *b;
*b = tmp;
printf("n values after swap a = %d nand b = %d", *a, *b);
}
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FUNCTION IN C PROGRAMMING

14. RECURSION
 Recursion is the process of repeating items in a self-similar way. In
programming languages, if a program allows you to call a function inside the
same function, then it is called a recursive call of the function.
 Common examples of where recursion is used
 Walking recursive data structures such as linked lists, binary trees, etc.
 Exploring possible scenarios in games such as chess
Recursion always consists of two main parts. A terminating case that indicates
when the recursion will finish and a call to itself that must make progress
towards the terminating case. 14
FUNCTION IN C PROGRAMMING

15. SYNTAX
int main()
{
callme( );
...
return 0;
}
void rec( )
{
statement 1;
...
rec( );
}
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16. WORKING OF RECURSION
// A C++ program to demonstrate working of recursion
#include<stdio.h>
void printFun(int test)
{
if (test < 1)
return;
else
{
cout << test << " ";
printFun(test-1); // statement 2
cout << test << " ";
return;
}
}
int main()
{
int test = 3;
printFun(test);
}
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FUNCTION IN C PROGRAMMING

17. REFERENCES
 https://www.tutorialspoint.com/cprogramming/c_recursion.
htm
 “Yashavant P. Kanetkar”, Let Us C - 14th Edition BPB
Publications ©2016, ISBN:8183331637 9788183331630
 https://fresh2refresh.com/
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18. THANK YOU