如何将在函数中定义的指针正确传递给作为函数参数给出的指针

Question

我对指针有问题。我尝试将板子（双指针）设置为gameboard->Board，并且在尝试打印时函数外部出现怪异的符号，因此我认为我做错了。

我将不胜感激能帮助您理解做这种事情的正确方法。

这里是代码：

typedef struct{
    int value;
    char sym;

}Cell;

typedef struct{
    int BoardSize;
    int BlockWidth;
    int BlockHeight;
    int erroneous;/*0- no error, 1- error*/
    Cell** Board;
}GameBoard;


void make9X9Board(GameBoard *gameboard){/*init to an empty 9X9 board*/
    int i;
    int j;
    Cell **board=(Cell**) malloc(sizeof(Cell)*9*9);/*allocate memory for the board*/
    for (i = 0; i < 9; i++) {
         board[i] = (Cell *) malloc(sizeof(Cell) * 9);
     }

    /*make an empty board*/
    for(i=0;i<9;i++){
        for(j=0;j<9;j++){
            board[i][j].value=0;
            board[i][i].sym=' ';
        }

    }

    /*free previous board*/
    for (i = 0; i < gameboard->BoardSize; i++) {
         free(gameboard->Board[i]);
     }
    free(gameboard->Board);

    /*init new gameboard values*/
    gameboard->BlockHeight=3;
    gameboard->BlockWidth=3;
    gameboard->BoardSize=9;
    gameboard->erroneous=0;
    gameboard->Board=board;

}

void edit(GameBoard *gameboard,Mode *mode, char *x, int isX, int MarkE){/*load a board to edit mode, if isX=0 we didn't get a path, else we did */

    if(isX==0){/*means the function works without path to file so make 9X9 empty board */
        make9X9Board(gameboard);
        *mode=EDIT_M;
        print_board(gameboard,*mode,MarkE);
        return;
    }
    /*else we got a path so work with it so just use solve with isEdit=1 for edit special cases*/
    solve(gameboard,mode,x,MarkE,1);
    *mode=EDIT_M;
    print_board(gameboard,*mode,MarkE);
}

int main(){

    Mode *mode=(Mode*)malloc(sizeof(Mode));
    char *x;
    int i;
    GameBoard* board;
    board=(GameBoard*) malloc(sizeof(GameBoard));/*further initialization when loading a certain board*/
    board->BlockHeight=3;
    board->BlockWidth=3;
    board->BoardSize=9;
    board->Board=(Cell**) malloc(sizeof(Cell)*9*(9));/*allocate memory for the board*/
    for (i = 0; i < 9; i++) {
        board->Board[i] = (Cell *) malloc(sizeof(Cell) * 9);
     }

    x="D:/Users/x.txt";
    *mode=INIT_M;

    edit(board,mode,x,0,0);
    print_board(board,*mode,0);


}

Answer 1

这不是一个答案，这里仅是在说明中做更多说明

从您的代码中，如果我加上：

typedef enum Mode { INIT_M, EDIT_M } Mode;

void print_board(GameBoard *gameboard,Mode mode, int MarkE)
{
  printf("%d %d %d %d\n", 
     gameboard->BoardSize, gameboard->BlockWidth,
     gameboard->BlockHeight, gameboard->erroneous);

  int i, j;
  Cell ** b = gameboard->Board;

  for (i = 0; i != gameboard->BlockHeight; i += 1) {
    for (j = 0; j != gameboard->BlockWidth; j += 1)
      printf("[%d '%c'] ", b[i][j].value, b[i][j].sym);
    putchar('\n');
  }
}

void solve(GameBoard *gameboard,Mode*  mode, char *x, int MarkE, int dummy)
{
}

能够进行编译和执行没有明显的问题：

bruno@bruno-XPS-8300:/tmp$ ./a.out
9 3 3 0
[0 ' '] [0 ' '] [0 ' '] 
[0 ' '] [0 ' '] [0 ' '] 
[0 ' '] [0 ' '] [0 ' '] 
9 3 3 0
[0 ' '] [0 ' '] [0 ' '] 
[0 ' '] [0 ' '] [0 ' '] 
[0 ' '] [0 ' '] [0 ' '] 
bruno@bruno-XPS-8300:/tmp$ 

以及valgrind下：

bruno@bruno-XPS-8300:/tmp$ valgrind ./a.out
==14595== Memcheck, a memory error detector
==14595== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==14595== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==14595== Command: ./a.out
==14595== 
9 3 3 0
[0 ' '] [0 ' '] [0 ' '] 
[0 ' '] [0 ' '] [0 ' '] 
[0 ' '] [0 ' '] [0 ' '] 
9 3 3 0
[0 ' '] [0 ' '] [0 ' '] 
[0 ' '] [0 ' '] [0 ' '] 
[0 ' '] [0 ' '] [0 ' '] 
==14595== 
==14595== HEAP SUMMARY:
==14595==     in use at exit: 1,324 bytes in 12 blocks
==14595==   total heap usage: 23 allocs, 11 frees, 3,644 bytes allocated
==14595== 
==14595== LEAK SUMMARY:
==14595==    definitely lost: 28 bytes in 2 blocks
==14595==    indirectly lost: 1,296 bytes in 10 blocks
==14595==      possibly lost: 0 bytes in 0 blocks
==14595==    still reachable: 0 bytes in 0 blocks
==14595==         suppressed: 0 bytes in 0 blocks
==14595== Rerun with --leak-check=full to see details of leaked memory
==14595== 
==14595== For counts of detected and suppressed errors, rerun with: -v
==14595== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
bruno@bruno-XPS-8300:/tmp$ 

所以问题不在您提供给我们的代码中