Answer :

#include<stdio.h>  //header file contains the function,decleraction and macro defination of key words used in code.

int main ()

{

int num1,num2,swap; //adressing the variables

num1=20;       //assining the values for variables

num2=10;      //assining the values for variables

printf("Before Swaining Num1 = %d and Num2=%d\n",num1,num2); //output

swap=num1;    /*swaping the numbers by using third variable.

                swaping means interchanging the value of variables*/

num1=num2;

num2=swap;

    printf("After Swaining Num1 = %d and Num2=%d\n",num1,num2); //output

}

Output :