Swapping of two numbers in C

Swapping means to interchange the value of two variables.For example if   variable a store 10 and another variable b store 20 then after swapping  b contains 10 and a contains 20. In c we can do the swapping in two way :- 

• using extra variable
• without using extra variable

Swapping of two numbers in C 

Program 1:Using extra variable

#include<stdio.h> 
void swap(int *a, int *b)
 {
   int temp; //extra variable
   temp = *a;
   *a = *b;
   *b = temp;
}
int main()
{
int a, b;
printf("nEnter the first number : ");
scanf("%d", &a);
printf("nEnter the Second number : ");
scanf("%d", &b);
swap(&a, &b);
printf("nValues after swapping ");
printf("nFirst number  : %d", a);
printf("nSecond number : %d", b);
return (0);
}

Program 2 : Without using extra variable.

#include <stdio.h>
 
int main()
{
   int a, b;
 
   printf("Enter two integers to swap\n");
   scanf("%d%d", &a, &b);
 
   a = a + b;
   b = a - b;
   a = a - b;
 
   printf("a = %d\nb = %d\n",a,b);
   return 0;
}

Program 2 : Using Pointer

#include <stdio.h>
 
int main()
{
   int x, y, *a, *b, temp;
 
   printf("Enter the value of x and y\n");
   scanf("%d%d", &x, &y);
 
   printf("Before Swapping\nx = %d\ny = %d\n", x, y);
 
   a = &x;
   b = &y;
 
   temp = *b;
   *b   = *a;
   *a   = temp;
 
   printf("After Swapping\nx = %d\ny = %d\n", x, y);
 
   return 0;
}

Program 4 :Using call by reference




#include <stdio.h>
 
void swap(int*, int*);
 
int main()
{
   int x, y;
 
   printf("Enter the value of x and y\n");
   scanf("%d%d",&x,&y);
 
   printf("Before Swapping\nx = %d\ny = %d\n", x, y);
 
   swap(&x, &y); 
 
   printf("After Swapping\nx = %d\ny = %d\n", x, y);
 
   return 0;
}
 
void swap(int *a, int *b)
{
   int temp;
 
   temp = *b;
   *b   = *a;
   *a   = temp;   
}




Program 2 : Using bitwise XOR


#include <stdio.h>
 
int main()
{
  int x, y;
 
 printf("Enter two integers to swap\n");




  scanf("%d%d", &x, &y);
 
  printf("x = %d\ny = %d\n", x, y);
 
  x = x ^ y;
  y = x ^ y;
  x = x ^ y;
 
  printf("x = %d\ny = %d\n", x, y);
 
  return 0;
}



Output