Program to Find Prime Numbers in a Given Range in C++

Finding Prime Numbers in a Range

A prime number is a natural number greater than 1 that has no divisors other than 1 and itself.

We will explore different methods to find all prime numbers within a given range using C++ programming.

Method 1: Using a for Loop

We iterate through the given range and check if each number is prime.

#include <iostream>
using namespace std;

bool isPrime(int num) {
    if (num < 2) return false;
    for (int i = 2; i * i <= num; i++) {
        if (num % i == 0)
            return false;
    }
    return true;
}

int main() {
    int start, end;
    cout << "Enter the range (start end): ";
    cin >> start >> end;
    
    cout << "Prime numbers between " << start << " and " << end << " are: ";
    for (int i = start; i <= end; i++) {
        if (isPrime(i)) {
            cout << i << " ";
        }
    }
    return 0;
}
            

Output:

Enter the range (start end): 10 20
Prime numbers between 10 and 20 are: 11 13 17 19