IsPrime

#include <iostream>
#include <math.h>


//Checking primality of a number using TRIAL DIVISION METHOD

using namespace std;

int main() {
    unsigned int n;
    cout << "Enter a Positive decimal number: ";
    cin >> n;
    if(n==0||n==1) {
        cout << endl << n << " is neither prime nor composite.\n";
        return 0;
    }
    for(int i=2;i<=sqrt(n);i++) { //Set i to be less than n if sqrt not available and use the below commented method
        if(n%i==0) {
            cout << endl << n << " is not a prime number.\n";
            return 0;
        }
        /* If sqrt function is not supported or cannot be used, take squares of the factors
        and make sure i is set to be less than n and not its square root.
        *****THIS WILL INCREASE THE TIME COMPLEXITY*****
         else if(i*i>n) {
            cout << endl << n << " is a prime number.\n";
            break;
        }*/
    }
    cout << endl << n << " is a prime number.\n";//Discard the statement if using the above commented method
    return 0;
}