#include <stdio.h>
int main()
{
int n, i, flag = 0;
printf("Enter a positive integer: ");
scanf("%d", &n);
// 0 and 1 are not prime numbers
if (n == 0 || n == 1)
{
printf("%d is not a prime number.", n);
}
else
{
for (i = 2; i <= n/2; ++i)
{
// If n is divisible by any number between 2 and n/2, it is not prime
if (n%i == 0)
{
flag = 1;
break;
}
}
if (flag == 0)
{
printf("%d is a prime number.", n);
}
else
{
printf("%d is not a prime number.", n);
}
}
return 0;
}
In this program, we first take a positive integer as input from the user. Then, we check if the number is 0 or 1, which are not prime numbers. If the number is neither 0 nor 1, we loop through all the numbers from 2 to n/2 and check if n is divisible by any of these numbers. If n is divisible by any of these numbers, we set a flag variable to 1 and break out of the loop. Finally, we check the value of the flag variable and print the appropriate message to indicate whether the number is prime or not.
