当这两个字符都是字符时，为什么我不能使用 strcat 将它们组合起来？

Question

我正在为 3ds 开发一款游戏，我希望它是一款 cmd 类型的游戏（我只是觉得喜欢）。我试图让这个 char 移动到我拥有的任何 x 和 y int 数字，但出现错误。这是我的代码。

/*
    Hello World example made by Aurelio Mannara for libctru
    This code was modified for the last time on: 12/12/2014 21:00 UTC+1
*/

#include <3ds.h>
#include <stdio.h>
#include <string.h>
int main(int argc, char **argv)
{
    gfxInitDefault();

    char player[1024] = "\x1b[";
    int tesx = 1;
    char tesxx = tesx + '0';
    char ot[] = ";";
    char oty[] = "H0";
    int test = 3;
    char testt = test + '0';
    //Initialize console on top screen. Using NULL as the second argument tells the console library to use the internal console structure as current one
    consoleInit(GFX_TOP, NULL);
    strcat(player, tesxx);
    strcat(player, ot);
    strcat(player, testt);
    strcat(player, oty);
    //Move the cursor to row 15 and column 19 and then prints "Hello World!"
    //To move the cursor you have to print "\x1b[r;cH", where r and c are respectively
    //the row and column where you want your cursor to move
    //The top screen has 30 rows and 50 columns
    //The bottom screen has 30 rows and 40 columns
    printf(player);

    // Main loop
    while (aptMainLoop())
    {
        //Scan all the inputs. This should be done once for each frame
        hidScanInput();

        //hidKeysDown returns information about which buttons have been just pressed (and they weren't in the previous frame)
        u32 kDown = hidKeysDown();

        if (kDown & KEY_START) break; // break in order to return to hbmenu

        // Flush and swap framebuffers
        gfxFlushBuffers();
        gfxSwapBuffers();

        //Wait for VBlank
        gspWaitForVBlank();
    }

    gfxExit();
    return 0;
}

这是我的错误。我对 C 很陌生，所以如果这是一个简单的错误，我很抱歉。我尝试搜索，但在网上找不到任何内容。

C:/Users/Jeremy/Desktop/gaame/source/main.c:24:9: warning: 'strcat' offset 0 is out of the bounds [0, 0] [-Warray-bounds]
   24 |         strcat(player, testt);
      |         ^~~~~~~~~~~~~~~~~~~~~
C:/Users/Jeremy/Desktop/gaame/source/main.c:22:9: warning: '__builtin_stpcpy' offset 0 is out of the bounds [0, 0] [-Warray-bounds]
   22 |         strcat(player, tesxx);
      |         ^~~~~~~~~~~~~~~~~~~~~

Answer 1

该函数strcat要求其两个参数都是指向有效字符串的指针，根据定义，该字符串是一个以空字符结尾的字符序列。

然而，在行

strcat(player, tesxx);

第二个函数参数tesxx不是指向有效字符串的指针。相反，它是一个简单的char.

因此，我建议您将此行更改为以下内容：

player[2] = tesxx;
player[3] = '\0';

如果该行之前的字符串长度不能保证为2，那么您可以这样写：

size_t len = strlen( player );
player[len+0] = tesxx;
player[len+1] = '\0';

或者，正如其他答案之一所建议的，您可以使用strncat它，它允许您将单个字符附加到字符串中：

strncat( player, &tesxx, 1 );

或者，您可以更改线路

strcat(player, tesxx);
strcat(player, ot);
strcat(player, testt);
strcat(player, oty);

至以下内容：

snprintf( player + 2, (sizeof player) - 2, "%c%s%c%s", tesxx, ot, testt, oty );

请参阅该函数snprintf以获取更多信息。

如果这些行之前的字符串长度不能保证为2，那么您可以这样写：

size_t len = strlen( player );
snprintf( player + len, (sizeof player) - len, "%c%s%c%s", tesxx, ot, testt, oty );

player您还可以使用以下函数构建整个字符串snprintf：

    char player[1024];
    int tesx = 1;
    char tesxx = tesx + '0';
    char ot[] = ";";
    char oty[] = "H0";
    int test = 3;
    char testt = test + '0';

snprintf( player, sizeof player, "\x1b[%c%s%c%s", tesxx, ot, testt, oty );