prime number c++ algorithm code example

Example 1: c++ prime number program

#include <iostream>
using namespace std;

int main() {
    int i, n;
    bool isPrime = true;

    cout << "Enter a positive integer: ";
    cin >> n;

    // 0 and 1 are not prime numbers
    if (n == 0 || n == 1) {
        isPrime = false;
    }
    else {
        for (i = 2; i <= n / 2; ++i) {
            if (n % i == 0) {
                isPrime = false;
                break;
            }
        }
    }
    if (isPrime)
        cout << n << " is a prime number";
    else
        cout << n << " is not a prime number";

    return 0;
}

Example 2: prime number c++

template<class T> bool isPrime(T n) 
{ 
	T i;
  	if(i<2) return false;
	for(i = 2; i * i <= n; i++) { 
    	if(n % i == 0)  return false; 
    } 
	return true; 
}