C++快速入门 第三十一讲：错误处理与调试2

让函数返回错误代码

实例：范围限制

 1 #include <iostream>
 2 #include <climits>
 3 
 4 using namespace std;
 5 class Factorial
 6 {
 7 public:
 8     Factorial(unsigned short num);
 9     unsigned long getFactorial();
10     bool inRange();
11     
12 private:
13     unsigned short num;
14 };
15 Factorial::Factorial(unsigned short num)
16 {
17     this->num = num;//传入的参数num值给了Factorial类中的属性num 
18 }
19 
20 unsigned long Factorial::getFactorial()
21 {
22     unsigned long sum = 1;
23     for(int i=1;i <= num; i++)
24     {
25         sum *= i;
26     }
27     return sum;
28 }
29 bool Factorial::inRange()
30 {
31     unsigned long max = ULONG_MAX;//ULONG_MAX在头文件climits中 
32     for(int i = num; i >= 1; --i)//将最大值ULONG_MAX除以输入的num阶乘 
33     {
34         max /= i;
35     }
36     if(max < 1)
37     return false;
38     else 
39     return true;
40 }
41 
42 int main()
43 {
44     unsigned short num = 0;
45     cout << "请输入一个整数：";
46     cin >> num;
47     
48     Factorial fac(num);
49     
50     if(fac.inRange())
51     {
52         cout << num << "的阶乘值是" << fac.getFactorial() << "\n\n";
53      } 
54      else
55      {
56          cout << "您所输入的值太大！\n\n";
57      }
58 }