




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:

By + and -
By * and /

Program 1: Using + and -
Let's see a simple c example to swap two numbers without using third variable.

#include
 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
#include
 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













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