如何在C/SDL2中处理多个文件中的结构/抽象数据类型

Question

我正在使用 SDL2 和 C 开发这个图形/游戏引擎。

我设法编写了游戏循环的所有基础代码，并将内容分成多个文件。当我尝试定义自己的数据类型（在本例中为结构）时出现了问题。我在 tad.h 和 tad.c 中有我的 struct (vector3) 定义和声明，但在使用此 vector3 类型创建变量时遇到问题。我尝试在主文件中声明此 ponto1，并且尝试在其他文件中将其用作全局变量，但出现一些错误。

我希望能够声明我自己的结构体和指向结构体的指针，但我是在 C 中使用多个文件这样的新手。以下是我收到的文件和问题： （PS：也欢迎有关如何更好地构建我的程序的建议）

tad.h：

#ifndef TAD
#define TAD

typedef struct vector3 Vector3;

#endif

tad.c：

#include <stdio.h>
#include <SDL2/SDL.h>

#include "./tad.h"
#include "./constants.h"
#include "./globals.h"

struct vector3 {
    float x;
    float y;
    float z;
};

globals.h：

extern SDL_Window* my_window;
extern SDL_Renderer* my_renderer;

extern int game_is_running;

extern Vector3 ponto1;

main.c

#include <stdio.h>
#include <SDL2/SDL.h>


#include "./constants.h"
#include "./globals.h"
#include "./tad.h"
#include "./init_and_destroy.h"
#include "./setup.h"
#include "./process_input.h"
#include "./update.h"
#include "./render.h"

SDL_Window* my_window = NULL;
SDL_Renderer* my_renderer = NULL;
int game_is_running = FALSE;

Vector3 ponto1;


int main() {
    
    game_is_running  = initialize_window(&my_window, &my_renderer);
    
    setup();

    while(game_is_running) {
        process_input();
        update();
        render();
    }

    destroy_window(my_window, my_renderer);

    return 0;
}

更新.c

#include "./constants.h"
#include "./globals.h"
#include "./tad.h"
#include "./update.h"

int last_frame_time = 0;

void update() {
    
    //caping frame rate
    int time_to_wait = FRAME_TARGET_TIME - (SDL_GetTicks() - last_frame_time);
    if (time_to_wait > 0 && time_to_wait <= FRAME_TARGET_TIME) {
        SDL_Delay(time_to_wait);
    }

    //delta time in seconds
    float delta_time = (SDL_GetTicks() - last_frame_time) / 1000.0f;

    last_frame_time = SDL_GetTicks();

//-------------------------------------------------------------------------------------

    ponto1.x += 20 * delta_time; //I'M TRYING TO ACCESS AND CHANGE THIS STRUCT

}

我得到的错误：

./src/./globals.h:6:8: error: unknown type name ‘Vector3’
    6 | extern Vector3 ponto1;
      |        ^~~~~~~
In file included from ./src/main.c:6:
./src/./globals.h:6:8: error: unknown type name ‘Vector3’
    6 | extern Vector3 ponto1;
      |        ^~~~~~~
./src/main.c:18:9: error: conflicting types for ‘ponto1’; have ‘Vector3’ {aka ‘struct vector3’}
   18 | Vector3 ponto1;
      |         ^~~~~~
In file included from ./src/main.c:6:
./src/./globals.h:6:16: note: previous declaration of ‘ponto1’ with type ‘int’
    6 | extern Vector3 ponto1;
      |                ^~~~~~
./src/main.c:18:9: error: storage size of ‘ponto1’ isn’t known
   18 | Vector3 ponto1;
      |         ^~~~~~
In file included from ./src/process_input.c:4:
./src/./globals.h:6:8: error: unknown type name ‘Vector3’
    6 | extern Vector3 ponto1;
      |        ^~~~~~~
In file included from ./src/render.c:5:
./src/./globals.h:6:8: error: unknown type name ‘Vector3’
    6 | extern Vector3 ponto1;
      |        ^~~~~~~
./src/render.c: In function ‘render’:
./src/render.c:16:44: error: request for member ‘x’ in something not a structure or union
   16 |     SDL_RenderDrawPoint(my_renderer, ponto1.x, 50);
      |                                            ^
In file included from ./src/setup.c:5:
./src/./globals.h:6:8: error: unknown type name ‘Vector3’
    6 | extern Vector3 ponto1;
      |        ^~~~~~~
./src/setup.c: In function ‘setup’:
./src/setup.c:11:11: error: request for member ‘x’ in something not a structure or union
   11 |     ponto1.x = 3;
      |           ^
In file included from ./src/update.c:5:
./src/./globals.h:6:8: error: unknown type name ‘Vector3’
    6 | extern Vector3 ponto1;
      |        ^~~~~~~
./src/update.c: In function ‘update’:
./src/update.c:26:11: error: request for member ‘x’ in something not a structure or union
   26 |     ponto1.x += 20 * delta_time;
      |           ^
make: *** [Makefile:2: build] Error 1

Answer 1

您收到错误，因为 globals.h 使用类型

Vector3

但当时尚未定义该类型。

您需要在 globals.h 中

#include "tad.h"

，因为它使用在那里定义的类型。

您看到的另一个问题是因为在包含 tad.h 的文件中并且它使用

Vector3

的字段，该类型引用的结构已被声明但未定义。您需要将结构体定义从 tad.c 移至 tad.h 中，以便其他文件可以使用它。