Question

write a program to take a number as input then check whether it is prime number or not

Answer 1

#include <stdio.h>
int main()
{
int n, i, flag = 0;

printf("Enter a positive integer: ");
scanf("%d", &n);

for(i = 2; i <= n/2; ++i)
{
// condition for nonprime number
if(n%i == 0)
{
flag = 1;
break;
}
}

if (n == 1)
{
printf("1 is neither a prime nor a composite number.");
}
else
{
if (flag == 0)
printf("%d is a prime number.", n);
else
printf("%d is not a prime number.", n);
}

return 0;
}