条件跳转或移动取决于未初始化的值

Question

我已经为这个问题苦苦挣扎了一段时间，寻找每一种可能的解决方案。我是C语言新手，所以不太难。我知道我有一些未初始化的变量，但我找不到它们。我正在尝试打印一个矩阵。这是构造函数：

BoardP createNewBoard(int width, int high)
{  

    BoardP board = (BoardP) malloc(sizeof(Board));

    if (board == NULL)
    {
        reportError(MEM_OUT);
        return NULL;
    }
    board->height = high;
    board->width = width;
    board->board = (char**) malloc(high * sizeof(char*));
    int i;
    for (i=0; i<high; i++)
    {
        board->board[i] = (char*) malloc(width * sizeof(char));
        if (board->board[i] == NULL)
        {
            freeTempBoard(board,i);
            return NULL;
        }
    }

    return board;
}

构造函数返回 BoardP，Board 的打印器，即：

typedef struct Board
{
    int width;
    int height;
    char **board;
} Board;

现在我无法尝试打印 board->board。我循环遍历矩阵，并为每个单元格调用此函数：

static void printChar(ConstBoardP board, int X, int Y)
{
    if (X>=board->height || Y>=board->width)
    {
        printf(" ");
    }
    else
    {
        printf("%c ",board->board[X][Y]); //!!THIS IS LINE 299 IN Board.c!!
    }
}

最后，这是我得到的错误：

==4931== Conditional jump or move depends on uninitialised value(s)
==4931==    at 0x4E973D9: _IO_file_overflow@@GLIBC_2.2.5 (fileops.c:880)
==4931==    by 0x4E6F01B: vfprintf (vfprintf.c:1614)
==4931==    by 0x4E75879: printf (printf.c:35)
==4931==    by 0x400D91: printChar (Board.c:299)
==4931==    by 0x400CED: printBoard (Board.c:284)
==4931==    by 0x400F1A: main (PlayBoard.c:19)
==4931== 
==4931== Conditional jump or move depends on uninitialised value(s)
==4931==    at 0x4E97401: _IO_file_overflow@@GLIBC_2.2.5 (fileops.c:887)
==4931==    by 0x4E6F01B: vfprintf (vfprintf.c:1614)
==4931==    by 0x4E75879: printf (printf.c:35)
==4931==    by 0x400D91: printChar (Board.c:299)
==4931==    by 0x400CED: printBoard (Board.c:284)
==4931==    by 0x400F1A: main (PlayBoard.c:19)
==4931== 
==4931== Conditional jump or move depends on uninitialised value(s)
==4931==    at 0x4E6F025: vfprintf (vfprintf.c:1614)
==4931==    by 0x4E75879: printf (printf.c:35)
==4931==    by 0x400D91: printChar (Board.c:299)
==4931==    by 0x400CED: printBoard (Board.c:284)
==4931==    by 0x400F1A: main (PlayBoard.c:19)

现在有另一个文件调用 createNewBoard，然后创建 printBoard(newBoard,0,0)。唯一可能未初始化的是 board->board，除此之外我没有任何想法。我不知道如何调试它。 我知道它有很多文字，但我找不到问题。任何想法将不胜感激

Answer 1

尝试：

for (i=0; i<high; i++)
{
    board->board[i] = (char*) malloc(width * sizeof(char));
    /* ... */
    memset(board[i], 0, width);
}

Answer 2

malloc 不会初始化内存，因此：

printf("%c ",board->board[X][Y]);

可能未初始化。使用 calloc 代替或在后面添加 memset

board->board[i] = (char*) malloc(width * sizeof(char));

Answer 3

在这一行：

board->board[i] = (char*) malloc(width * sizeof(char));

...您为板行分配空间，但您从未真正初始化该数组中的值。使用 memset(board[i], 0, width) 或显式循环数组来设置值。

（此外，作为一种风格问题，您不需要 强制转换 malloc的返回值。）