练习91

#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;
}