Answer to Question #181782 in C++ for tan

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

#include <iostream>

using namespace std;

int is_prime(int n)
{
   int i;
   if (n <= 1) return 0;
   if (n % 2 == 0 && n > 2) return 0;
   for (i = 3; i < n / 2; i += 2)
   {
      if (n % i == 0)
         return 0;
   }
   return 1;
}


int main()
{
    cout<<is_prime(19)<<endl;
    cout<<is_prime(1)<<endl;
    cout<<is_prime(51)<<endl;
    cout<<is_prime(-13)<<endl;
    return 0;
}