c++ - 为什么我会收到 "is not a class or namespace"错误

Question

我有一个生成错误的文件

"Block" is not a class or a namespace name

在线

typedef Block::point point;

但是，我确信这是一个我已经创建并#included 在下面的文件中的类

'纹理.h'。

    #pragma once
#include "Block.h"
#include <iostream>
#include <vector>
#include <GL/glut.h>
#include "lodepng.h"

using namespace std;
typedef Block::point point;


class Texture
{



public:
    Texture(int width, int height, string filename);//initialises our texture and loads its pixeldata into a buffer
    Texture(void);
    ~Texture(void);

    void draw(point centerPoint, point dimensions);

    unsigned int w;//width of our imagefile
    unsigned int h;

    GLuint texID;//the ID we will give OGL for this particular texture.

private:
    vector<unsigned char> image;
    void texGLInit();
};

另外，这里是有问题的 block.h 文件。

#pragma once
#include <GL/glut.h> 
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include "Texture.h"

class Block
{


public:
    struct point
    {
        GLfloat x, y;
    };

    enum State  {STATIC, FALLING, SELECTED};

    enum Colour {RED, BLUE, PURPLE, GREEN, YELLOW, DEAD};

    Block(void);
    ~Block(void);

    Block(int gridPosX, int gridPosY, point offset);
    point gridPos;//the blocks designated position in the 8x8 array
    point centerPos;//the blocks coordinates for the actual purpose of drawing

    State blockState;//the state of the block
    Colour blockColour;//the colour of the block

    void move();//checks whether the block is in a falling state and moves it appropriately
    void drawBlock();//no need to include the drawing coords as parameters. the block knows where it should be. The grid will simply tell it to draw itself.

private:
    void fall();//decrements the blocks position
    void assignRandomColour();//assigns a random colour to the block dependant upon its' texture
    void generateWorldPos();//gets our block a center position, for us to later to use to draw it.
    //the above function will also inherently define the size of each cell in the grid. I'm thinking each
    //cell should be 40x40. So each cell will be offset initially by 20px by 20px. 



    point gridOffset;



};

我不知道为什么我会为肯定存在的类收到此错误。提前致谢。

Answer 1

我看到循环包含:Block.h 包含 Texture.h，其中包含 Block.h。

在这个网站上搜索“cyclic header dependency”，你会看到很多关于这个的主题，在那里你可以找到解决这个难题的方法，最常见的是使用前向声明成员数据的类和指针声明。类的前向声明可帮助您避免包含标题，数据的指针声明可帮助您定义封闭类。这只是一个提示，现在搜索上述主题以获得详细答案。