异常层次结构

#include <iostream>

using namespace std;

const int DefaultSize = 10;

// 动态数组，
class Array
{
public:
Array(int itsSize = DefaultSize);
~Array() { delete [] pType; }

// 运算符重载，
int& operator[] (int offSet); // offSet 是代表下标的数，
const int& operator[] (int offSet) const;

// 访问器，accessors
int GetitsSize() const { return itsSize; }
// 异常类。
class xBoundary{};
class xSize
{
public:
xSize(){}
xSize(int size) : itsSize(size) {}
~xSize(){}
int GetSize() { return itsSize; }
virtual void PrintError()   // 这是虚函数，
{
cout << "下标发生错误：" << itsSize << endl;
}
protected:
int itsSize;
};
class xZero : public xSize
{
public:
xZero(int size) : xSize(size){}
virtual void PrintError()
{
cout << "下标不能是0."<< endl;
}
};
class xNegative : public xSize
{
public:
xNegative(int size):xSize(size){}
virtual void PrintError()
{
cout << "下标不能是负的."<< endl;
}
};
class xTooSmall : public xSize
{
public:
xTooSmall(int size) :xSize(size){}
virtual void PrintError()
{
cout << "下标不能是小于10."<< endl;
}
};
class xTooBig : public xSize
{
public:
xTooBig(int size) :xSize(size){}
virtual void PrintError()
{
cout << "下标不能大于50000."<< endl;
}
};
private:
int *pType;
int itsSize;

};

int& Array::operator[](int offSet)
{
int size = this->GetitsSize();
if(offSet >= 0 && offSet < size)
return pType[offSet];
throw xBoundary();
}

const int& Array::operator [](int offSet) const
{
int size = this->GetitsSize();
if(offSet >= 0 && offSet < size)
return pType[offSet];
throw xBoundary();
}

Array::Array(int size) : itsSize(size)
{
if(size == 0)
throw xZero(size);
else if(size < 0)
throw xNegative(size);
else if(size < 10)
throw xTooSmall(size);
else if(size > 90000)
throw xTooBig(size);

pType = new int[size];
for(int i = 0; i < size; i++)
pType[i] = 0;

}

int main()
{
try
{
Array a;
/*Array b(12);*/
Array intArray(20);
Array b(2);
/*b[4] = 20;
b[20] = 50;
cout << b[4] << endl;*/
for(int j = 0; j < 100; j++)
{
intArray[j] = j;
cout << "intArray[" << j << "]  ok...." << endl;
}
}

catch(Array::xBoundary)
{
cout << "下标越界了，" << endl;
}
catch(Array::xSize& exp)
{
exp.PrintError();   // 这是一个多态性，是一个虚函数，
}
/*catch(Array::xZero theException)
{
cout << "下标不能小于0， " << endl;
}
catch(Array::xNegative theException)
{
cout << "下标不能小于0，" << theException.GetSize() << endl;
}
catch(Array::xTooSmall theException)
{
cout << "下标不能小于10， " << theException.GetSize() << endl;
}
catch(Array::xTooBig theException)
{
cout << "下标不能大于90000，" << theException.GetSize() << endl;
}*/

catch(...) // 这个是捕获剩余的其它的异常，
{
cout << "发生未知异常？" << endl;
}

cout << "Done. " << endl;

return 0;
}