Difference Between Call by Value And Call by Reference

February 15, 2023

Call by Value Vs Call by Reference

On this page we will discuss about difference between call by value and call by reference. On this page we will also write program for both to understand the difference between them in detail. These are the methods to pass parameter in a function.Hence understanding call by value and call by reference is very important to understand the basics of functionin C++.

Difference Between Call by Value And Call by Reference

Call By Value	Call By Reference
In this passing the value of Variable.	In this passing the address of Variable.
Can’t change the value of actual argument using formal argument.	Can change the value of actual argument using formal argument.
No pointers are used.	Pointers are used.
It requires more memory.	It requires less memory.
It is less sufficient.	It is more sufficient.

Loop Types in C++

Decision Making in C++

Array in C++

String in C++

Function in C++

Call by Value

Example

Run

#include <iostream>
using namespace std;
void swap (int, int);
int main ()				//caller function
{
  int a = 2, b = 3;
  swap (a, b);			//fun_call
  cout << "In calle:after swapping a=" << a << " b=" << b;
}

void
swap (int a, int b)
{
  b = (a + b) - (a = b);	//swap logic in a single line 

  cout << "In called:after swapping a=" << a << " b=" << b;
  cout << endl;
}

Output:

In calle:after swapping a:2 b:3
In called:after swapping a:3 b:2

Here ‘a’ ,’b’ in main function is different from ‘a’,’b’ from swap() function.
Just data is copied, both are having different scopes and different memory locations
Hence changes in the swap() ‘a’, ‘b’ will not affect the main ‘a’, ‘b’

call by address

Sending the address of variables from caller to calle function is called call-by-address
Any changes made in function definition will also affect the change in the caller function

Example

Run

#include <iostream> 
using namespace std;
void swap (int *x, int *y)
{
  int swap;
  swap = *x;
  *x = *y;
  *y = swap;
}

int main ()
{
  int x = 2, y = 3;
  cout << "Value of x before swap is: " << x << endl;
  cout << "Value of y before swap is: " << y << endl;
  swap (&x, &y);
  cout << "Value of x is: " << x << endl;
  cout << "Value of y is: " << y << endl;
  return 0;
}

Output:

Value of x before swap is: 2
Value of y before swap is: 3
Value of x is: 3
Value of y is: 2

In this address of main() ‘a’, ‘b’ is passed to swap() and stored in pointers ‘c’, ‘d’
Hence * c,*d points to a,b respectively and having same locations
Here a and *c and b and *d both are the same, any changes in either caller or called function will reflect other

Prime Course Trailer

Related Banners

Get PrepInsta Prime & get Access to all 200+ courses offered by PrepInsta in One Subscription

Get over 200+ course One Subscription

Courses like AI/ML, Cloud Computing, Ethical Hacking, C, C++, Java, Python, DSA (All Languages), Competitive Coding (All Languages), TCS, Infosys, Wipro, Amazon, DBMS, SQL and others

Difference Between Call by Value And Call by Reference

Call by Value Vs Call by Reference

Difference Between Call by Value And Call by Reference

Call by Value

Example

call by address

Example

Prime Course Trailer

Related Banners

Get over 200+ course One Subscription

Checkout list of all the video courses in PrepInsta Prime Subscription

Checkout list of all the video courses in PrepInsta Prime Subscription