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

#include <iostream>
#include <climits>

using namespace std;
class Factorial
{
public:
    Factorial(unsigned short num);
    unsigned long getFactorial();
    bool inRange();
    
private:
    unsigned short num;
};
Factorial::Factorial(unsigned short num)
{
    this->num = num;//传入的参数num值给了Factorial类中的属性num 
}

unsigned long Factorial::getFactorial()
{
    unsigned long sum = 1;
    for(int i=1;i <= num; i++)
    {
        sum *= i;
    }
    return sum;
}
bool Factorial::inRange()
{
    unsigned long max = ULONG_MAX;//ULONG_MAX在头文件climits中 
    for(int i = num; i >= 1; --i)//将最大值ULONG_MAX除以输入的num阶乘 
    {
        max /= i;
    }
    if(max < 1)
    return false;
    else 
    return true;
}

int main()
{
    unsigned short num = 0;
    cout << "请输入一个整数：";
    cin >> num;
    
    Factorial fac(num);
    
    if(fac.inRange())
    {
        cout << num << "的阶乘值是" << fac.getFactorial() << "\n\n";
     } 
     else
     {
         cout << "您所输入的值太大！\n\n";
     }
}