Swap 2 Numbers Using Macros: C Program

Today lets learn how to swap two integer numbers(using a temporary variable) using Macros in C.

Video Tutorial: Swap 2 Numbers Using Macros: C Program

Source Code: Swap 2 Numbers Using Macros: C Program

#include<stdio.h>

#define SWAP(x, y, temp) temp = x; x = y; y = temp;

int main()
{
    int a, b, temp;

    printf("Enter 2 integer numbers\n");
    scanf("%d%d", &a, &b);

    printf("Before swapping: a = %d and b = %d\n", a, b);

    SWAP(a, b, temp);

    printf("After swapping: a = %d and b = %d\n", a, b);

    return 0;
}

Output:
Enter 2 integer numbers
20
50
Before swapping: a = 20 and b = 50
After swapping: a = 50 and b = 20

Logic To Swap Two Numbers

First value of a is transferred to temp;
Next value of b is transferred to a.
Next value of temp is transferred to b.

That’s how value of a and b are swapped using a temporary variable.

Note: Preprocessor replaces the macro template(SWAP(a, b, temp)) with its corresponding macro expansion(temp = x; x = y; y = temp;) before passing the source code to the compiler.

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