38.其他的重载

程序1：

#pragma warning(disable:4996)
#include <iostream>
using namespace std;

class Maker
{
public:
    Maker()
    {
        a = 0;
    }
    void SetA(int val)
    {
        a = val;
    }

    //没有返回值，也没有void
    operator bool()
    {
        if( a <= 0 )
        {
            return false;
        }

        return true;
    }
public:
    int a;
};

void test()
{
    Maker m;

    if( m )
    {
        cout << "真" << endl;
    }
    else
    {
        cout << "假" << endl;
    }
}

int main()
{
    test();
    system("pause");
    return EXIT_SUCCESS;
}

输出结果：

假
请按任意键继续. . .

---

---

程序2：

#pragma warning(disable:4996)
#include <iostream>
using namespace std;

class Maker
{
public:
    Maker()
    {
        a = 0;
    }
    void SetA(int val)
    {
        a = val;
    }

    //没有返回值，也没有void
    operator bool()
    {
        if( a <= 0 )
        {
            return false;
        }

        return true;
    }

    bool operator!()
    {
        if( a <= 0 )
        {
            return true;
        }

        return false;
    }

    operator int()
    {
        return 10;
    }
public:
    int a;
};

void test()
{
    Maker m;
    m.SetA(10);
    if( m )
    {
        cout << "真" << endl;
    }
    else
    {
        cout << "假" << endl;
    }
    if( !m )
    {
        cout << "真" << endl;
    }
    else
    {
        cout << "假" << endl;
    }

    int b = (int)m;
    cout << b << endl;
}

int main()
{
    test();
    system("pause");
    return EXIT_SUCCESS;
}

输出结果：

真
假
10
请按任意键继续. . .