What is the difference between "call by value" and "call by reference"? explain with example in c language.

Call by reference

In an function if the variables are passed as reference variables this means that the variables are pointing to the original arguments.So the changes made in the function on the reference variables will be reflected back on the original arguments.

For example:-

#include<stdio.h>

void swap(&int f,&int s)

{

   int t=f;

   f=s;

  s =temp;  

}

int main()

{

int n,m;

n=45;

m=85;

swap(n,m);

printf("%d %d",m,n);

return 0;  

}

the values of m and n will get swapped.  

Call by value

In this program the values of m and n will not get swapped because they are passed by value.So duplicate copies of m and n will be created and manipulation will be done on them.

#include<stdio.h>

void swapv(int f,int s)

{

   int t=f;  

   f=s;  

   s=temp;

}

int main()

{  

int n,m;

n=45;

m=85;

swapv(n,m);

printf("%d %d",n,m);

return 0;

}