proxygen
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 }
bool IsPrime(int n)
Definition: sample1.cc:47
int Factorial(int n)
Definition: sample1.cc:37