异常的层次结构(继承在异常中的应用)

深藏阁楼爱情的钟 2023-07-17 02:48 46阅读 0赞

1.  异常是类 – 创建自己的异常类
2.  异常派生
3.  异常中的数据：数据成员
4.  按引用传递异常
    
     *  在异常中使用虚函数

案例：设计一个数组类 MyArray，重载\[\]操作，

数组初始化时，对数组的个数进行有效检查

1.  index<0 抛出异常eNegative  
2.  index = 0 抛出异常 eZero

3）index>1000抛出异常eTooBig

4）index<10 抛出异常eTooSmall

5）eSize类是以上类的父类，实现有参数构造、并定义virtual void printErr()输出错误(多态)。

具体代码如下：

#include <iostream>
    using namespace std;
    
    class MyArray
    {
    public:
    	MyArray(int len);
    	~MyArray();
    public:
    	int & operator[](int index);
    	int getLen();
    
    	class eSize
    	{
    	public:
    		eSize(int size)
    		{
    			m_size = size;
    		}
    		virtual void printErr()
    		{
    			cout << "size:" << m_size << " ";
    		}
    	protected:
    		int m_size;
    	};
    	class eNegative : public eSize
    	{
    	public:
    		eNegative(int size) : eSize(size)
    		{
    			;
    		}
    		virtual void printErr()
    		{
    			cout << "eNegative 类型 size:" << m_size << " ";
    		}
    	};
    	class eZero : public eSize
    	{
    	public:
    		eZero(int size) : eSize(size)
    		{
    			;
    		}
    		virtual void printErr()
    		{
    			cout << "eZero 类型 size:" << m_size << " ";
    		}
    	};
    	class eTooBig : public eSize
    	{
    	public:
    		eTooBig(int size) : eSize(size)
    		{
    			;
    		}
    		virtual void printErr()
    		{
    			cout << "eTooBig 类型 size:" << m_size << " ";
    		}
    	};
    	class eTooSmall : public eSize
    	{
    	public:
    		eTooSmall(int size) : eSize(size)
    		{
    			;
    		}
    		virtual void printErr()
    		{
    			cout << "eTooSmall 类型 size:" << m_size << " ";
    		}
    	};
    
    private:
    	int *m_space;
    	int m_len;
    };
    
    
    MyArray::MyArray(int len)
    {
    	if (len  < 0)
    	{
    		throw eNegative(len);
    	}
    	else if (len == 0)
    	{
    		throw eZero(len);
    	}
    	else if (len > 1000)
    	{
    		throw eTooBig(len);
    	}
    	else if (len < 3)
    	{
    		throw eTooSmall(len);
    	}
    	m_len = len;
    	m_space = new int[len];
    }
    
    MyArray::~MyArray()
    {
    	if (m_space != NULL)
    	{
    		delete [] m_space;
    		m_space = NULL;
    		m_len = 0;
    	}
    }
    
    int & MyArray::operator[](int index)
    {
    	return m_space[index];
    }
    
    int MyArray::getLen()
    {
    	return m_len;
    }
    
    void main()
    {
    	try
    	{
    		MyArray a(-5);
    		for (int i=0; i<a.getLen(); i++)
    		{
    			a[i] = i+1;
    			printf("%d ", a[i]);
    		}
    	}
    	catch(MyArray::eSize &e)
    	{
    		//cout <<  "len的大小: " << e.eSize();
    		e.printErr();
    	}
    	catch (...)
    	{
    	}
    	cout<<"hello..."<<endl;
    	system("pause");
    	return ;
    }
    
    // 不推荐
    void main51()
    {
    	try
    	{
    		MyArray a(-5);
    		for (int i=0; i<a.getLen(); i++)
    		{
    			a[i] = i+1;
    			printf("%d ", a[i]);
    		}
    	}
    	catch(MyArray::eNegative e)
    	{
    		cout << "eNegative 类型异常" << endl;
    	}
    	catch(MyArray::eZero e)
    	{
    		cout << "eZero 类型异常" << endl;
    	}
    	catch(MyArray::eTooBig e)
    	{
    		cout << "eTooBig 类型异常" << endl;
    	}
    	catch(MyArray::eTooSmall e)
    	{
    		cout << "eTooSmall 类型异常" << endl;
    	}
    	catch (...)
    	{
    	}
    	cout<<"hello..."<<endl;
    	system("pause");
    	return ;
    }