时间戳

首页 > 解决方案 > 可变大小的对象可能没有被初始化（但有一个扭曲）C

c - 可变大小的对象可能没有被初始化（但有一个扭曲）C

问题描述

这段代码...

//variables
int tileSize = 20;
int playerSize = 5;
int map[tileSize][tileSize] =
{
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
};

...给我这个错误

mateusz@mateusz-MS-7693:~/Desktop/3ds-Projects/Platform_game$ make
main.c
/home/mateusz/Desktop/3ds-Projects/Platform_game/source/main.c: In function 'main':
/home/mateusz/Desktop/3ds-Projects/Platform_game/source/main.c:21:5: error: variable-sized object may not be initialized
21 |     int map[tileSize][tileSize] =
   |     ^~~
make[1]: *** [/opt/devkitpro/devkitARM/base_rules:85: main.o] Error 1
make: *** [Makefile:155: all] Error 2

但是当我在地图变量大小中放入“20”而不是“tileSize”时，如下所示：

//variables
int tileSize = 20;
int playerSize = 5;
int map[20][20] =
{
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
};

错误消失，代码编译得很好。

这是完整的代码：

#include <citro2d.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#define SCREEN_WIDTH  400
#define SCREEN_HEIGHT 240

int main(int argc, char* argv[]){

gfxInitDefault();
C3D_Init(C3D_DEFAULT_CMDBUF_SIZE);
C2D_Init(C2D_DEFAULT_MAX_OBJECTS);
C2D_Prepare();
consoleInit(GFX_BOTTOM, NULL);
C3D_RenderTarget* top = C2D_CreateScreenTarget(GFX_TOP, GFX_LEFT);

//variables
int tileSize = 20;
int playerSize = 5;
int map[20][20] =
{
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,1},
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
};
float Pos[2] = {100,100};

u32 PlayerColor = C2D_Color32(0x10,0x20,0xF0,0xFF);
u32 tileColor   = C2D_Color32(0x10,0xF0,0x90,0xFF);
u32 clrClear    = C2D_Color32(0x10,0x10,0x10,0xFF);

// Main loop
while (aptMainLoop())
{
    hidScanInput();
    u32 kDown = hidKeysDown();
    if (kDown & KEY_START) break;

    
    C3D_FrameBegin(C3D_FRAME_SYNCDRAW);
    C2D_TargetClear(top, clrClear);
    C2D_SceneBegin(top);
    
    C2D_DrawRectSolid(Pos[0], Pos[1],0,playerSize,playerSize, PlayerColor);
    for(int i = 0;i<SCREEN_WIDTH/tileSize;i++){
        for(int y = 0;y<SCREEN_HEIGHT/tileSize;y++){
            if(map[i][y]){
                C2D_DrawRectSolid(i*tileSize, y*tileSize,0,tileSize,tileSize, tileColor);
            }
        }
    }

    C3D_FrameEnd(0);
}

gfxExit();
C2D_Fini();
C3D_Fini();
return 0;
}

为什么我不能将“tileSize”变量放在地图大小内？

标签： c

解决方案

tileSize不是编译时常量值。它是一个运行时变量，其值在编译时未知。

在 C 中，如果您希望能够在定义时初始化数组，则需要将编译时常量作为数组大小。

最常见的方法是使用宏：

#define TILE_SIZE 20

int map[TILE_SIZE][TILE_SIZE] = { ... };

另一种可能性是使用枚举：

enum
{
    tileSize = 20
};

int map[tileSize][tileSize] = { ... };

推荐阅读