test/gtest-1.6.0/samples/sample1.cc

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  29
  30 // A sample program demonstrating using Google C++ testing framework.
  31 //
  32 // Author: wan@google.com (Zhanyong Wan)
  33
  34 #include "sample1.h"
  35
  36 // Returns n! (the factorial of n).  For negative n, n! is defined to be 1.
  37 int Factorial(int n) {
  38   int result = 1;
  39   for (int i = 1; i <= n; i++) {
  40     result *= i;
  41   }
  42
  43   return result;
  44 }
  45
  46 // Returns true iff n is a prime number.
  47 bool IsPrime(int n) {
  48   // Trivial case 1: small numbers
  49   if (n <= 1) return false;
  50
  51   // Trivial case 2: even numbers
  52   if (n % 2 == 0) return n == 2;
  53
  54   // Now, we have that n is odd and n >= 3.
  55
  56   // Try to divide n by every odd number i, starting from 3
  57   for (int i = 3; ; i += 2) {
  58     // We only have to try i up to the squre root of n
  59     if (i > n/i) break;
  60
  61     // Now, we have i <= n/i < n.
  62     // If n is divisible by i, n is not prime.
  63     if (n % i == 0) return false;
  64   }
  65
  66   // n has no integer factor in the range (1, n), and thus is prime.
  67   return true;
  68 }