swap logic c

// program to swap 2 numbers using different methods

#include<stdio.h>
#include<conio.h>

// method that swaps numbers using + and - operations
void swap1(int *num1, int *num2){
    *num1 = *num1 + *num2;
    *num2 = *num1 - *num2;
    *num1 = *num1 - *num2;

    return;
}

// method that swaps numbers using * and / operations
void swap2(int *num1, int *num2){
    *num1 = *num1 * *num2;
    *num2 = *num1 / *num2;
    *num1 = *num1 / *num2;

    return;
}

// method that swaps numbers using ^ ( ex-or ) operations
void swap3(int *num1, int *num2){
    *num1 = *num1 ^ *num2;
    *num2 = *num1 ^ *num2;
    *num1 = *num1 ^ *num2;

    return;
}

// method that swaps numbers using temp variables
void swap4(int *num1, int *num2){
    int temp;
    temp = *num1;
    *num1 = *num2;
    *num2 = temp;

    return;
}

void main(){

    int a = 10, b = 15;
    float c = 10.999,d = 11.222;
    printf("Values before swapping are a = %d and b = %d", a,b);

    swap1(&a, &b);
    printf("\nValues after swapping using swap1 are :");
    printf("\na = %d \nb = %d",a,b);

    swap2(&a, &b);
    printf("\nValues after swapping using swap2 are :");
    printf("\na = %d \nd = %d",a,b);

    swap3(&a, &b);
    printf("\nValues after swapping using swap3 are :");
    printf("\na = %d \nb = %d",a,b);

    swap4(&a, &b);
    printf("\nValues after swapping using swap4 are :");
    printf("\na = %d \nb = %d",a,b);

    return;
}