Answer to Question #181283 in C++ for Darren

Question

A positive integer n is said to be prime (or, "a prime") if and only if n is greater than 1 and is divisible only by 1 and n. For example, the integers 17 and 29 are prime, but 1 and 38 are not prime. Write a function named "is_prime" that takes a positive integer argument and returns as its value the integer 1 if the argument is prime and returns the integer 0 otherwise. Thus, for example:

cout << is_prime(19) << endl;    // will print 1

cout << is_prime(1) << endl;     // will print 0

cout << is_prime(51) << endl;   // will print 0

cout << is_prime(-13) << endl; // will print 0

Answer 1

bool is_prime(int num)
{
    if(num == 2 || num == 3 || num == 5 || num == 7)
        return true;
    else if(num == 1 || num%2 == 0 || num%3 == 0 || num%5 == 0 || num%7 == 0)
        return false;
    else
        return true;
}