#include <stdio.h>   
 
void swap(int , int); //prototype of the function    
int main()   
{   
    int a = 10;   
    int b = 20;    
    printf("Before swapping the values in main a = %d, b = %d\n",a,b);     // printing the value of a and b  
    swap(a,b);   
    printf("After swapping values in main a = %d, b = %d\n",a,b);  // The value of actual parameters do     
                                      not change by changing the formal parameters in call by value, a = 10, b = 20   
}   
 
void swap (int a, int b)   
{   
    int temp;    
 
    temp = a;   
    a=b;   
    b=temp;   
    printf("After swapping values in function a = %d, b = %d\n",a,b);   
    // Formal parameters, a = 20, b = 10    
}