异常

try检测异常

throw抛出

catch处理异常

C++处理异常

#include <iostream>

class wrong//表示错误类型
{

};

int intdiv(int a, int b)
{
    try
    {
        if (!b)
        {
            throw wrong();
        }

        int c = a / b;
        return a / b;
    }
    catch (wrong)
    {
        std::cout << "除法异常已经处理" << std::endl;
        return -1;
    }
}

void main()
{
    int x, y;
    std::cin >> x >> y;

    std::cout << intdiv(x, y) << std::endl;
}

类中异常

#include <iostream>

class box
{
public:
    box(int data) :a(data)
    {
        std::cout << "开始构造" << std::endl;

        if (data < 100)
        {
            throw small();
        }
        else if (data > 10000)
        {
            throw big();
        }
    }
    class big {};
    class small {};
private:
    int a;
};

void main()
{
    try
    {
        box newbox(200);
    }
    catch (box::big)
    {
        std::cout << "长度太长" << std::endl;
    }
    catch (box::small)
    {
        std::cout << "长度太短" << std::endl;
    }
}

异常类的派生

适用于处理违反了2个规则的异常

#include <iostream>
#include <string>

class box//正方体
{
public:
    box(int data)
    {
        std::cout << "开始构造" << std::endl;

        if (data == 0)
        {
            zero z1(22);
            z1.seterror(21);

            throw z1;
        }
        else if (data > 0 && data<100)
        {
            throw small();
        }
        else  if (data>10000)
        {
            throw big();
        }
        else if (data > 100 && data < 10000)
        {
            a = data;
        }
        else
        {
            throw wrong{};
        }
    }
    
    int  gettiji()
    {
        return  a*a*a;
    }

    class wrong {};
    class big {};
    class small {};

    class zero :public small//两种错误的处理方式都接受
    {
    public:
        int errorcode;
        zero(int i) :errorcode(i)
        {

        }
        void  seterror(int i)
        {
            errorcode = i;
        }
    };
private:
    int a;//变长
};

void main()
{

    try
    {
        box newbox(0);
    }

    catch (box::wrong)
    {
        std::cout << "正方体长度异常" << std::endl;
    }
    catch (box::big)
    {

        std::cout << "正方体长度太长" << std::endl;
    }
    catch (box::zero w)
    {
        if (w.errorcode == 22)
        {
            std::cout << "22号错误正方体长度不可以为0" << std::endl;
        }
        else
        {
            std::cout << "fei22号错误正方体长度不可以为0" << std::endl;
        }

    }
    catch (box::small)
    {
        std::cout << "正方体长度taiduan" << std::endl;
    }
}

MFC处理异常

void openfile()
{
    TRY
    {
        CFile file(_T("F:\users\123.txt"), CFile::modeRead);//尝试动作，如果异常，抛出异常
    }
        CATCH(CFileException, e)//文件的异常
    {
        if (e->m_cause == CFileException::fileNotFound)
        {
            cout << "文件不存在，请认真检查";
        }
    }
    END_CATCH
}