1 // Copyright 2005, Google Inc. 2 // All rights reserved. 3 // 4 // Redistribution and use in source and binary forms, with or without 5 // modification, are permitted provided that the following conditions are 6 // met: 7 // 8 // * Redistributions of source code must retain the above copyright 9 // notice, this list of conditions and the following disclaimer. 10 // * Redistributions in binary form must reproduce the above 11 // copyright notice, this list of conditions and the following disclaimer 12 // in the documentation and/or other materials provided with the 13 // distribution. 14 // * Neither the name of Google Inc. nor the names of its 15 // contributors may be used to endorse or promote products derived from 16 // this software without specific prior written permission. 17 // 18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 30 // A sample program demonstrating using Google C++ testing framework. 31 // 32 // Author: wan (at) 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 } 69
