C Program To Swap Two Numbers Using Functions

#include<stdio.h>
void swap(int *,int *);
int main()
{
    int n1,n2;
    printf("Input 1st number : ");
    scanf("%d",&n1);
    printf("Input 2nd number : ");
    scanf("%d",&n2);
    printf("Before swapping: n1 = %d, n2 = %d ",n1,n2);
	//pass the address of both variables to the function.
    swap(&n1,&n2);
    printf("\nAfter swapping: n1 = %d, n2 = %d \n\n",n1,n2);
    return 0;
}
void swap(int *p,int *q)
{
	int tmp;
    tmp = *p; // tmp store the value of n1
    *p=*q;    // *p store the value of *q that is value of n2
    *q=tmp;   // *q store the value of tmp that is the value of n1
}

Output:

Input 1st number : 2
Input 2nd number : 4
Before swapping: n1 = 2, n2 = 4
After swapping: n1 = 4, n2 = 2

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