Question

write a program to explain the concept of call by value and call by reference?
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Answer 1

Explanation:

Call by value:

• The value of the actual parameter is passed to the formal parameter which means the value of the variable is used.

• In which the coder does not modify the value of the actual parameter.
• Separate memory is allocated to the actual and formal parameters.

Program:

#include<stdio.h>  

void change(int num) {

printf("Before adding value inside function num=%d \n", num);  

num=num+100;  

printf("After adding value inside function num=%d \n", num);  

}  

int main() {  

int x=100;  

printf("Before function call x=%d \n", x);  

change(x);//passing value in function  

printf("After function call x=%d \n", x);  

return 0;  

}  

Output:

Before function call x=100  

Before adding value inside function num=100  

After adding value inside function num=200  

After function call x=100

Call by reference:

• In which the address of the variable is passed as an actual parameter.
• The actual parameter can be modified by the formal parameter.
• The same memory is shared among both the formal and actual parameters.

Program:

#include<stdio.h>  

void change(int *num) {  

printf("Before adding value inside function num=%d \n",*num);  

(*num) += 100;  

printf("After adding value inside function num=%d \n", *num);  

}  

int main() {  

int x=100;  

printf("Before function call x=%d \n", x);  

change(&x);//passing reference in function  

printf("After function call x=%d \n", x);  

return 0;  

}

Output:

Before function call x=100  

Before adding value inside function num=100  

After adding value inside function num=200  

After function call x=200