Argument-Passing

Argument-Passing by Value

<arg_by_value.c>


#include <stdio.h>

void main ( )
{
        int a = 2;
        
        printf ("Value of 'a' in main( ) before calling MyFunction( ) is %d\n", a);
        MyFunction (a);
        printf ("Value of 'a' in main( ) after calling MyFunction( ) is %d\n", a);
}

void MyFunction (int a)
{
        printf ("Value of 'a' inside MyFunction( ) before being changed is %d\n", a);
        a = 9;
        printf ("Value of 'a' inside MyFunction( ) after being changed is %d\n", a);
}

Here's the output:

UNIX prompt >> a.out
Value of 'a' in main( ) before calling MyFunction( ) is 2

Value of 'a' inside MyFunction( ) before being changed is 2
Value of 'a' inside MyFunction( ) after being changed is 9

Value of 'a' in main( ) after calling MyFunction( ) is 2
UNIX prompt >>

Argument-Passing by Reference

<arg_by_reference.c>



#include <stdio.h>

void main ( )
{
  	int a = 2;
	
  	printf ("Value of 'a' in main( ) before calling MyFunction( ) is %d\n", a);
  	MyFunction (&a);
  	printf ("Value of 'a' in main( ) after calling MyFunction( ) is %d\n", a);
}
	
void MyFunction (int *a)
{
  	printf ("Value of 'a' inside MyFunction( ) before being changed is %d\n", *a);
  	*a = 9; 
  	printf ("Value of 'a' inside MyFunction( ) after being changed is %d\n", *a);
}

Here's the output:

UNIX prompt >> a.out
Value of 'a' in main( ) before calling MyFunction( ) is 2

Value of 'a' inside MyFunction( ) before bing changed is 2
Value of 'a' inside MyFunction( ) after bing changed is 9

Value of 'a' in main( ) after calling MyFunction( ) is 9
UNIX prompt >>