c++ - 我构造子类对象的方式有什么问题？

这是我的子类：

class BackGround :public Object{
public:
BackGround(int y){
    character.Load(_T("wallpaper.png"));
    x = 0;
    this->y = y;
    direct = 0;
    width = 1200;
    height = 375;
}
};

我的基类：

class Object{
public:
CImage character;
int x;
int y;
int direct;
int speed;
int width;
int height;
int Xcenter;
int Ycenter;

Object(){}

void draw(HDC hDC){
    character.Draw(hDC, x, y, width, height, 0, direct*height,width, height);
}
};

当我创建BackGround类的对象时，
BackGround Bg1(0); BackGround Bg2(-WINDOW_HEIGHT);

出现错误：

1>  MainFrm.cpp
1>c:\users\desktop\mfcgame\mfcgame\childview.h(46): error C2059: syntax error: 'const'
1>c:\users\desktop\mfcgame\mfcgame\childview.h(47): error C2059: syntax error:“-”
1>  MFCGame.cpp
1>c:\users\desktop\mfcgame\mfcgame\childview.h(46): error C2059: syntax error: 'const'
1>c:\users\desktop\mfcgame\mfcgame\childview.h(47): error C2059: syntax error:“-”
1>  ChildView.cpp
1>c:\users\desktop\mfcgame\mfcgame\childview.h(46): error C2059: syntax error: 'const'
1>c:\users\desktop\mfcgame\mfcgame\childview.h(47): error C2059: syntax error:“-”
1>c:\users\desktop\mfcgame\mfcgame\childview.cpp(67): error C2228: left of '.draw' must have class/struct/union type
1>c:\users\desktop\mfcgame\mfcgame\childview.cpp(68): error C2228: left of '.draw' must have class/struct/union type
1>c:\users\desktop\mfcgame\mfcgame\childview.cpp(116): error C2228: left of '.y' must have class/struct/union type
1>c:\users\desktop\mfcgame\mfcgame\childview.cpp(118): error C2228: left of '.y' must have class/struct/union type
1>c:\users\desktop\mfcgame\mfcgame\childview.cpp(120): error C2228: left of '.y' must have class/struct/union type
1>c:\users\desktop\mfcgame\mfcgame\childview.cpp(122): error C2228: left of '.y' must have class/struct/union type

最佳答案

我想你有

class CChildView : public CWnd
{
    // ...
    BackGround Bg1(0);                // Line 46
    BackGround Bg2(-WINDOW_HEIGHT);   // Line 47
};

这是声明成员变量的不正确语法。
（编译器认为这些看起来像成员函数的声明。）

如果您使用的是C ++ 11，则可以编写

class CChildView : public CWnd
{
    // ...
    BackGround Bg1 {0};
    BackGround Bg2 {-WINDOW_HEIGHT};
};

带有花括号，或者您可以初始化构造函数的初始化程序列表中的成员，该列表可在所有C ++版本中使用：

class CChildView : public CWnd
{
    CChildView();
    // ...
    BackGround Bg1;
    BackGround Bg2;
};

// ...

CChildView::CChildView() : Bg1(0), Bg2(-WINDOW_HEIGHT)
{
    // ...
}

background

c++ - 我构造子类对象的方式有什么问题？