Example: Naive Prime Number Finder in C

// Naive Prime Number Finder
#include <stdio.h>
#include <stdbool.h> // For boolean type

int main() {
    int lower_bound, upper_bound;

    // Step 1: Get user input for the range
    printf("Enter the lower bound of the range: ");
    scanf("%d", &lower_bound);
    printf("Enter the upper bound of the range: ");
    scanf("%d", &upper_bound);

    printf("Prime numbers between %d and %d are: ", lower_bound, upper_bound);

    // Step 2: Iterate through each number in the range
    for (int num = lower_bound; num <= upper_bound; num++) {
        // Step 3: Handle special cases: numbers less than 2 are not prime
        if (num <= 1) {
            continue; // Skip numbers that are 1 or less
        }

        // Step 4: Check for divisibility from 2 up to num-1
        bool is_prime = true;
        for (int i = 2; i < num; i++) {
            if (num % i == 0) {
                is_prime = false; // Found a divisor, so not prime
                break;            // No need to check further
            }
        }

        // Step 5: If no divisors were found, print the number
        if (is_prime) {
            printf("%d ", num);
        }
    }
    printf("\n");

    return 0;
}