71-75.个人练习。

c++个人练习

#include <iostream>using namespace std;class Exception{public:Exception(){}    virtual ~Exception(){}    virtual void PrintError() = 0;};class OutOfMemory : public Exception{public:    OutOfMemory(){}    ~OutOfMemory(){}    virtual void PrintError();};void OutOfMemory::PrintError(){    cout << "Out of Memory!!\n";}class RangeError : public Exception{public:    RangeError(unsigned long number){BadNum = number;}    ~RangeError(){}    virtual void PrintError();    virtual unsigned long GetNumber() { return BadNum; }    virtual void SetNumber(unsigned long number) {BadNum = number;}private:    unsigned long BadNum;};void RangeError::PrintError(){    cout << "Number out of range. You used " << GetNumber() << " !\n";}void fn1();unsigned int * fn2();void fn3(unsigned int *);int main(){    try    {fn1();    }    catch (Exception& theException)    {theException.PrintError();    }    return 0;}unsigned int * fn2(){    unsigned int *n = new unsigned int;if (n == 0)throw OutOfMemory();return n;}void fn1(){unsigned int *p = fn2();fn3(p);cout << "The number is : " << *p << endl;delete p;}void fn3(unsigned int *p){long Number;cout << "Enter an integer(0~~1000): ";cin >> Number;if (Number > 1000 || Number < 0)throw RangeError(Number);*p = Number;}