Example: Check Prime Number in C

// Check Prime Number
#include <stdio.h>
#include <math.h> // Required for sqrt()

// Function to check if a number is prime
int isPrime(int num) {
    // Step 1: Handle base cases for numbers less than or equal to 1
    if (num <= 1) {
        return 0; // Not prime
    }
    // Step 2: Loop from 2 up to the square root of the number
    // If any number divides 'num' evenly, it's not prime
    for (int i = 2; i <= sqrt(num); i++) {
        if (num % i == 0) {
            return 0; // Not prime
        }
    }
    // Step 3: If no divisors found, the number is prime
    return 1; // Prime
}

int main() {
    int number = 7; // Example number
    if (isPrime(number)) {
        printf("%d is a Prime number.\n", number);
    } else {
        printf("%d is not a Prime number.\n", number);
    }

    number = 10; // Another example
    if (isPrime(number)) {
        printf("%d is a Prime number.\n", number);
    } else {
        printf("%d is not a Prime number.\n", number);
    }
    return 0;
}