sample1.cc File Reference

#include "sample1.h"

Go to the source code of this file.

Functions
int	Factorial (int n)
bool	IsPrime (int n)

Function Documentation

int Factorial

(

int

n

)

Definition at line 37 of file sample1.cc.

References i.

                     {
  int result = 1;
  for (int i = 1; i <= n; i++) {
    result *= i;
  }

  return result;
}

bool IsPrime

(

int

n

)

Definition at line 47 of file sample1.cc.

References i.

                    {
  // Trivial case 1: small numbers
  if (n <= 1) return false;

  // Trivial case 2: even numbers
  if (n % 2 == 0) return n == 2;

  // Now, we have that n is odd and n >= 3.

  // Try to divide n by every odd number i, starting from 3
  for (int i = 3; ; i += 2) {
    // We only have to try i up to the squre root of n
    if (i > n/i) break;

    // Now, we have i <= n/i < n.
    // If n is divisible by i, n is not prime.
    if (n % i == 0) return false;
  }

  // n has no integer factor in the range (1, n), and thus is prime.
  return true;
}