C++学习笔记（三）--继承中的异常处理

继承中的异常处理

#include<iostream>
using namespace std;

//原始方法

class Arrary
{
public:
    Arrary(int);
    ~Arrary();
    int &operator[](int dex);
    int getlen();

    class Size
    {};
    class SizeErro
    {};
    class SizeZero
    {};
    class SizeToSmall
    {};
    class SizeToLarge
    {};



public:
    int m_len;
    int *m_space;
};
Arrary::Arrary(int len)//构造函数没有返回值，通过异常进行处理是常用的手段
{
    m_len = len;
    m_space = new int[len];
    if (len < 0) throw SizeErro();
    else if (len = 0) throw SizeZero();
    else if (len <= 2) throw SizeToSmall();
    else if (len > 100) throw SizeToLarge();
}

Arrary::~Arrary()
{
    delete[] m_space;
    m_len = 0;
    m_space = NULL;
}
int Arrary::getlen()
{
    return m_len;
}
int &Arrary::operator[](int dex)
{
    return m_space[dex];
}


void main()
{
    try
    {
        Arrary a(1);
        for (int i = 0; i < a.getlen();i++)
        {
        a[i] = i + 1;
        cout << a[i] << endl;
        }
    }
    catch (Arrary::SizeToSmall e)
    {
        cout << "SizeToSmall" << endl;
    }
    catch (...)
    {
    }
    system("pause");
}

使用继承

class Arrary
{
public:
    Arrary(int);
    ~Arrary();
    int &operator[](int dex);
    int getlen();

    class Size
    {
    public:
        virtual string printSize()
        {
            return "Size";
        }
    };
    class SizeErro:public Size
    {
        virtual string printSize()
        {
             return "SizeErro";
        }
    };
    class SizeZero :public Size
    {
        virtual string printSize()
        {
             return "SizeZero";
        }
    };
    class SizeToSmall :public Size
    {
        virtual string printSize()
        {
             return "SizeToSmall";
        }
    };
    class SizeToLarge :public Size
    {
        virtual string printSize()
        {
             return "SizeToLarge";
        }
    };

public:
    int m_len;
    int *m_space;
};
Arrary::Arrary(int len)//构造函数没有返回值，通过异常进行处理是常用的手段
{
    m_len = len;
    m_space = new int[len];
    if (len < 0) throw SizeErro();
    else if (len = 0) throw SizeZero();
    else if (len <= 2) throw SizeToSmall();
    else if (len > 100) throw SizeToLarge();
}

Arrary::~Arrary()
{
    delete[] m_space;
    m_len = 0;
    m_space = NULL;
}
int Arrary::getlen()
{
    return m_len;
}
int &Arrary::operator[](int dex)
{
    return m_space[dex];
}


void main()
{
    try
    {
        Arrary a(1);
        for (int i = 0; i < a.getlen();i++)
        {
        a[i] = i + 1;
    //  cout << a[i] << endl;
        }
    }
    catch (Arrary::Size &e)
    {
        cout << "Size" <<e.printSize()<< endl;
    }
    catch (...)
    {
        cout << "未知类型" << endl;

    }
    system("pause");
}