Program 56 - CSU1128 - CSE 2026 - Shoolini University

Program for swapping of two numbers entered by the user through call by value method

Explanation

The program demonstrates that swapping two numbers using call by value does not work. The values of the variables in the main function remain unchanged after attempting to swap them in a separate function.

Header

The code begins with including the standard input-output header file using #include <stdio.h>.

Function Declaration

The program declares a function swap to attempt to swap two integers:

void swap(int x, int y);: Declares the function with two integer parameters x and y.

Function Definition

The program defines the swap function:

int temp = x;: Stores the value of x in a temporary variable temp.
x = y;: Assigns the value of y to x.
y = temp;: Assigns the value of temp (original value of x) to y.
printf("Inside swap function: x = %d, y = %d\n", x, y);: Prints the swapped values of x and y inside the swap function.

Variable Declaration

The main() function is defined, and two variables are declared:

int a, b;: Variables to hold the values entered by the user.

Program Description

The program prints a description message for the user to understand its functionality.

User Input

The user is prompted to enter the values of a and b:

printf("Enter the value for a and b: ");: Prompts the user to enter the values of a and b.
scanf("%d %d", &a, &b);: Reads the values entered by the user and stores them in a and b.

Before Swap

The program prints the values of a and b before attempting to swap them:

printf("Before swap attempt in main: a = %d, b = %d\n", a, b);: Prints the values of a and b before the swap attempt.

Swap Attempt

The program calls the swap function to attempt to swap the values of a and b:

swap(a, b);: Calls the swap function with a and b as arguments.

After Swap

The program prints the values of a and b after attempting to swap them:

printf("After swap attempt in main: a = %d, b = %d\n", a, b);: Prints the values of a and b after the swap attempt, showing that they remain unchanged.

Program End

The program ends with return 0; to indicate successful execution.

Code

                    
/*
 * -----------------------------------------------------------
 * Logic Building with Computer Programming (CSU1128)
 * Instructor: Dr. Pankaj Vaidya | Author: Divya Mohan
 * 
 * This code is a part of the educational initiative by dmj.one
 * with aim of empowering and inspiring learners in the field of
 * Computer Science and Engineering through the respective courses.
 * 
 * (c) 2022, Divya Mohan for dmj.one. All rights reserved.
 * -----------------------------------------------------------
 */

#include <stdio.h>

// Swap function that attempts to swap using call by value
void swap(int x, int y) {
    int temp = x;
    x = y;
    y = temp;
    printf("Inside swap function: x = %d, y = %d\n", x, y); // This will show swapped values
}

int main() {
    printf("\n\n Program for demonstrating that swapping of two numbers using call by value method does not work. \n\n");

    int a, b;

    printf("Enter the value for a and b: ");
    scanf("%d %d", &a, &b);

    printf("Before swap attempt in main: a = %d, b = %d\n", a, b);

    swap(a, b);  // Trying to swap using call by value

    printf("After swap attempt in main: a = %d, b = %d\n", a, b);  // The values remain unchanged

    return 0;
}

Output

Program for swapping of two numbers entered by the user through call by value method.

Enter the value for a and b: 12 43
Before: a = 12, b = 43
After: a = 43, b = 12