Write a C program to swap to numbers without using third variable

// Write a C program to swap two numbers using third variable.
    #include<stdio.h> 
    int main(){
        int a, b, temp;
        printf("Enter the value of a : ");
        scanf("%d", &a);
        printf("Enter the value of b : ");
        scanf("%d", &b);
        // Before swapping the value of a and b.
        printf("Before Swapping the value of a = %d\tb = %d\n", a, b);
        a = a + b;
        b = a - b;
        a = a - b;
        // using temp to swap storing a to temp and b to a then moving temp to b. 
        // After swapping the value of a and b.
        printf("\nAfter Swapping the value of a = %d\tb = %d", a, b);
        return 0;
    }

The above code is swap two number given from the user. In this program takes input from the user a and b using the scanf() function and swap two numbers.

#include<stdio.h>

The above line of code includes the standard input/output library which is used to display the output and takes input from the user.

int main() {

Every program start from the main function(). The main() is the entry point for all programs.

int a, b, temp;

Declares the three integer variables named a, ,b and temp.

printf("Enter the value of a : ");

Prompt or message to the user to enter the value of a.

scanf("%d", &a);

Read the value for a using the scanf() function from the user.

printf("Enter the value of b : ");

Prompt to the user to enter the value of b using printf() function.

scanf("%d", &b);

Read the value of b from the user using the scanf() function.

printf("Before Swapping the value of a = %d\tb = %d\n", a, b);

Prompt or display the Before swapping the value of a and b using printf() function.

a = a + b;
    b = a - b;
    a = a - b;

These lines of code swap the number to each other. a = a + b store the sum of value both numbers, b = a - b store the value of of a - b here a is the updated value use, a = a - b store the value of a - b here a and b are the updated value used. So after those steps the value swapped.

printf("\nAfter Swapping the value of a = %d\tb = %d", a, b);

Prompt to the user to After swapping the value of a and b.

return 0;
            }

Program is successfully executed and returns the value 0.

Algorithm

1. Start
2. Declare variable a, b, and temp as integers.
3. Prompt to the user enter the value of a using the printf() function, Read the input value for a using scanf() function.
4. Prompt to the user enter the value of b, Read the input value for b.
5. Print the value of a and b before swapping the value.
6. SET a = a + b
7. SET b = a - b;
8. SET a = a - b;
9. Prompt to the user after swapping the value of a and b.
10. End.

Pseudocode

// Pseudocode
            1. Start
            2. Declare a, b, and c as integers.
            3. Display "Enter the value of a : "
            4. Read input for a using scanf()
            5. Display "Enter the value of b : "
            6. Read input for b using scanf()
            7. Display "Before Swapping the value of a and b"
            8. a = a + b;
            9. b = a - b;
            10. a = a - b;
            11. Display "After swapping the value of a and b"
            12. End