我是整个编程领域的新手。即使我以为我已经掌握了类及其包含的基本概念,但我无法弄清楚我在这里做错了什么。我制作了自己的名为Grid的类,它看起来像这样:

--- Grid.h ---

class Grid{

public:

Grid(HWND wnd);

public:

void paint(CDC &dc, int sqr, bool axis);            //paint the grid
void tag(CDC &dc);

private:
    int square;                                     //square size
    CRect frame;                                    //client area size
};


--- Grid.cpp ---

#include "stdafx.h"
#include "Grid.h"


Grid::Grid(HWND wnd)
    {
    CRect rect;
    GetClientRect(wnd, &rect);                  // get client area size
    frame.left = rect.right / 2 - 387;          // fit frame to margin
    frame.right = frame.left + 774;
    frame.top = rect.bottom - 874;
    frame.bottom = rect.bottom - 100;

}

void Grid::paint(CDC &dc, int sqr, bool axis){

square = sqr;                               // paint grid
CPen penWhite;
penWhite.CreatePen(PS_SOLID, 1, RGB(255, 255, 255));
dc.SelectObject(&penWhite);
dc.Rectangle(frame);

dc.MoveTo(frame.left + square, frame.top);
for (int i = 1; i < 18; i++){
    dc.LineTo(frame.left + square * i, frame.bottom);
    dc.MoveTo(frame.left + square + square * i, frame.top);
}

dc.MoveTo(frame.left, frame.top + square);
for (int i = 1; i < 18; i++){
    dc.LineTo(frame.right, frame.top + square * i);
    dc.MoveTo(frame.left, frame.top + square + square * i);
}

[...]


现在,我想做的是从另一个类中添加该类的对象。您可能已经猜到过,这是一个MFC应用程序,应该利用我随Grid提供的功能。因此我加了

--- MainFrm.cpp ---

[...]

// CMainFrame construction/destruction


CMainFrame::CMainFrame()
{
    // TODO: add member initialization code here
    Grid theGrid{ GetSafeHwnd() };
}

CMainFrame::~CMainFrame()
{
}

[...]


稍后我在其中致电:

void CMainFrame::OnPaint()
{
CPaintDC dc(this);   // get device context for paint

// get current window size
CRect rect;
GetClientRect(&rect); // get current client area size

// fill background black
CBrush brushBlack;
brushBlack.CreateSolidBrush(RGB(0, 0, 0));
dc.SelectObject(&brushBlack);
dc.FillRect(rect, &brushBlack);

// paint grid
theGrid.paint(dc, 43, 1);
ReleaseDC(&dc);

}  // end OnPaint()


...但是编译器给我错误C2065:'theGrid':未声明的标识符
而Intellisense在咆哮TheGrid.paint(dc,43,1);

我在这里做错了什么?我只想从MainFrm内部创建一个Grid对象,每个函数都可以访问该对象。

亲切的问候,
米申

最佳答案

Grid theGrid{ GetSafeHwnd() };


在构造函数中声明,因此仅获得局部作用域。您必须在构造函数外部声明它,并在构造函数上对其进行初始化,例如:

--.h file--
public class CMainFrame{
    Grid theGrid;

    [...]

--.cpp file---
CMainFrame::CMainFrame() :
    theGrid(GetSafeHwnd())
{}

关于c++ - 尽管包含但无法访问该类,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/35942176/

10-14 09:27