Example: C program to display prime numbers between two intervals using function

// C program to display prime numbers between two intervals using function
#include <stdio.h>

// @custom function to find the prime numbers between intervals
int GeneratePrimeNumbers(int low_number, int high_number) {
    int flag, temp;

    // this will swap the value of intervals between each other
    // if low_number is greater then high_number
    if (low_number > high_number) {
        temp;
        temp = low_number;
        low_number = high_number;
        high_number = temp;
    }

    printf("\nThe prime numbers between %d and %d are: ", low_number, high_number);

    for (int i = low_number; i <= high_number; i++) {
        flag = 0;

        // this will ignore numbers less than 2
        if (i <= 1) {
            continue;
        }

        // if low_number is a non-prime number, flag will be 1
        for (int j = 2; j <= i / 2; j++) {
            if (i % j == 0) {
                flag = 1;
                break;
            }
        }

        if (flag == 0)
            printf("%d ", i);
    }
    printf("\n");

    return 0;
}

// @driver function to call & print the primer numbers
int main() {
    int low_number, high_number;

    printf("Enter the two intervals:\n");
    scanf("%d %d", &low_number, &high_number);

    // @call the custom function to print the numbers
    GeneratePrimeNumbers(low_number, high_number);
    return 0;
}