What is difference between Call by value and Call by reference?

There are two different methods for passing a variable in function as a parameter:

1.Call by value:  we pass copy of actual variables in function as a parameter. Any changes on parameters inside the function will not effect the actual variable.

#include<stdio.h>

void main(){

    int a=5,b=10;

    change(a,b);

    printf("%d      %d",a,b); 

    

} 

void change(int a,int b){

    a=a+b;
    b=a-b;
   a=a-b;

}

Output: 5    10

2.Call by reference: we pass memory address of  actual variables in function as a parameter. Hence if we make any changes on parameters inside the function will effect the actual variable.

#include<stdio.h>

int main(){

    int a=5,b=10;

    change(&a,&b);

    printf("%d %d",a,b);

    return 0;

} 

void swap(int *a,int *b){

    int  *temp;

    *temp =*a;

    *a=*b;

    *b=*temp;

}

Output: 10 5