This code checks if a number is prime or not. It takes user input for a number, then uses a while loop to check if it is divisible by any number from 2 to half the input number. If it is not divisible by any, it prints that the number is prime, otherwise it prints that it is not prime.

1. Checking whether the number is prime or not :
#include<stdio.h>
intmain(void)
{
intx=0;
inta=2;
intnum1;
printf("Enteranynumbern");
scanf("%d",&num1);
while(a<=num1/2){
if(num1%a==0){
x++;
break;}
a++;
}
if(x==0)
printf("Numberisprimen");
else
printf("Numberisnotprimen");
return0;
}