C PROGRAMMING EXAMPLES

c program to swap two numbers

C program to swap two numbers with and without using third variable, swapping in c using pointers and functions (Call by reference) , swapping means interchanging. For example if in your c program you have taken two variable a and b where a = 4 and b = 5, then before swapping a = 4, b = 5 after swapping a = 5, b = 4
In our c program to swap numbers we will use a temp variable to swap two numbers. Swapping is used in sorting that is when we wish to arrange numbers in a particular order either in ascending order or in descending order.

Swaping of two numbers in c

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

Swapping of two numbers without third variable

You can also swap two numbers without using temp or temporary or third variable. In that case c program will be as shown :-

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

To understand above logic simply choose a as 7 and b as 9 and then do what is written in program. You can choose any other combination of numbers as well. Sometimes it's a good way to understand a program.

Swap two numbers using pointers

#include<stdio.h>
 
main()
{
   int x, y, *a, *b, temp;
 
   printf("Enter the value of x and y ");
   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;
}

Swapping numbers using call by reference

In this method we will make a function to swap numbers.

#include<stdio.h>
 
void swap(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;   
}

Output of code: