bloaty/third_party/googletest/googletest/samples/sample1.cc

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// Copyright 2005, Google Inc.
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// A sample program demonstrating using Google C++ testing framework.
 
#include "sample1.h"
 
// Returns n! (the factorial of n).  For negative n, n! is defined to be 1.
int Factorial(int n) {
  int result = 1;
  for (int i = 1; i <= n; i++) {
    result *= i;
  }
 
  return result;
}
 
// Returns true if n is a prime number.
bool IsPrime(int n) {
  // 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 square 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;
}