 # C Program to swap two numbers without third variable

#### C Program to swap two numbers without third variable:

We can swap two numbers without using third variable. There are two common ways to swap two numbers without using third variable:

1. By + and –
2. By * and /
##### Program 1: Using + and –

Let’s see a simple c example to swap two numbers without using third variable.

#include<stdio.h>

int main()

{

int a=10, b=20;

printf(“Before swap a=%d b=%d”,a,b);

a=a+b;//a=30 (10+20)

b=a-b;//b=10 (30-20)

a=a-b;//a=20 (30-10)

printf(“\nAfter swap a=%d b=%d”,a,b);

return 0;

}

Output:

```Before swap a=10 b=20
After swap a=20 b=10
```
##### Program 2: Using * and /

Let’s see another example to swap two numbers using * and /.

#include<stdio.h>

#include<stdlib.h>

int main()

{

int a=10, b=20;

printf(“Before swap a=%d b=%d”,a,b);

a=a*b;//a=200 (10*20)

b=a/b;//b=10 (200/20)

a=a/b;//a=20 (200/10)

system(“cls”);

printf(“\nAfter swap a=%d b=%d”,a,b);

return 0;

}

Output:

```Before swap a=10 b=20
After swap a=20 b=10

```