c - 链表和堆栈以及段错误

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第一次发布有关堆栈溢出的问题，所以要友善。我正在尝试为学校编写一个程序。该程序假设获取一个数据集并将其变成一个迷宫。我收到的错误是 putty 中的段错误，但我正在使用的 IDE 中不是段错误。不知道该怎么办或如何处理。我尝试将 printf 语句放在任何地方，但它们都没有真正出现，没有意义。也许是因为功能本身导致了故障，不确定是哪个部分。

//代码开始************************************************ **********************

#include <stdio.h>
#include <stdlib.h>
typedef int bool;
#define FALSE 0
#define TRUE  1

typedef struct mazeStruct
{
    char **arr; /* allows for a dynamic 2-D maze of any size */
    int xsize, ysize;
    int xstart, ystart;
    int xend, yend;
    bool end;
} maze;

struct linkedStruct
{
    int x;
    int y;
    bool Unvisited;
    struct linkedStruct* next;
};

typedef struct linkedStruct linked;
typedef linked* linkedPtr;

void push(linkedPtr* hd, int Xval, int Yval)
{
    linkedPtr ptr = (linkedPtr) malloc(sizeof(linked));
    ptr->x = Xval;
    ptr->y = Yval;
    ptr->Unvisited = FALSE;
    ptr->next = *hd;
    *hd = ptr;
}

int isEmpty(linkedPtr hd)
{
    if (hd == NULL)
        return TRUE;
    else
        return FALSE;
}

int top(linkedPtr hd)
{
    return (hd->x && hd->y);
}

void pop(linkedPtr* hd)
{
    linkedPtr ptr = (linkedPtr) malloc(sizeof(linked));

    ptr->x = NULL;
    ptr->y = NULL;
    ptr->Unvisited = TRUE;
    ptr->next = *hd;
    *hd = ptr;
    free(ptr);
}

int main(int argc, char **argv)
{
    maze m1;
    linkedPtr head = NULL;

    int xpos, ypos;
    int i, j;
    m1.end = FALSE;

    FILE *src;
    //FILE *src = fopen ("mazeData1.txt",'r');

    /* verify the proper number of command line arguments were given */
    if (argc != 2)
    {
        printf("Usage: %s <input file name>\n", argv[0]);
        exit(-1);
    }

    /* Try to open the input file. */
    if ((src = fopen(argv[1], "r")) == NULL)
    {
        printf("Can't open input file: %s", argv[1]);
        printf("Standard Error.\n");
        exit(-1);
    }

    /* read in the size, starting and ending positions in the maze */
    fscanf(src, "%d %d", &m1.xsize, &m1.ysize);
    if (m1.xsize < 1 || m1.ysize < 1)
    {
        printf("Size has to be 1 or above.\n");
        fscanf(src, "%d %d", &m1.xsize, &m1.ysize);
    }
    fscanf(src, "%d %d", &m1.xstart, &m1.ystart);
    if (m1.xstart > m1.xsize || m1.ystart > m1.ysize || m1.xstart < 1
            || m1.ystart < 1)
    {
        printf("The start has to be within the maze.\n");
        fscanf(src, "%d %d", &m1.xstart, &m1.ystart);
    }
    fscanf(src, "%d %d", &m1.xend, &m1.yend);
    if (m1.xend > m1.xsize || m1.yend > m1.ysize || m1.xend < 1 || m1.yend < 1)
    {
        printf("The end has to be within the maze.\n");
        fscanf(src, "%d %d", &m1.xend, &m1.yend);
    }

    if (m1.xend == NULL || m1.yend == NULL)
    {
        printf("Error: Need at least three lines of input");
        exit(-1);
    }

    /* print them out to verify the input */
    printf("size: %d, %d\n", m1.xsize, m1.ysize);
    printf("start: %d, %d\n", m1.xstart, m1.ystart);
    printf("end: %d, %d\n", m1.xend, m1.yend);

    /* allocate the maze */
    m1.arr = (char **) malloc(sizeof(char *) * (m1.xsize + 2));
    for (i = 0; i < m1.xsize + 2; i++)
        m1.arr[i] = (char *) malloc(sizeof(char) * (m1.ysize + 2));

    /* initialize the maze to empty */
    for (i = 0; i < m1.xsize + 2; i++)
        for (j = 0; j < m1.ysize + 2; j++)
            m1.arr[i][j] = '.';

    /* mark the borders of the maze with *'s */
    for (i = 0; i < m1.xsize + 2; i++)
    {
        m1.arr[i][0] = '*';
        m1.arr[i][m1.ysize + 1] = '*';
    }
    for (i = 0; i < m1.ysize + 2; i++)
    {
        m1.arr[0][i] = '*';
        m1.arr[m1.xsize + 1][i] = '*';
    }

    /* mark the starting and ending positions in the maze */
    m1.arr[m1.xstart][m1.ystart] = 's';
    m1.arr[m1.xend][m1.yend] = 'e';

    /* mark the blocked positions in the maze with *'s */
    while (fscanf(src, "%d %d", &xpos, &ypos) != EOF)
    {
        if (xpos > m1.xsize || ypos > m1.ysize || xpos < 1 || ypos < 1
                || (xpos == m1.xstart && ypos == m1.ystart)
                || (xpos == m1.xend && ypos == m1.yend))
        {
            printf(
                    "Error: X or Y is: out of range or is on the end or is on the start\n");
            continue;
        }
        m1.arr[xpos][ypos] = '*';
    }

    /* print out the initial maze */
    for (i = 0; i < m1.xsize + 2; i++)
    {
        for (j = 0; j < m1.ysize + 2; j++)
            printf("%c", m1.arr[i][j]);
        printf("\n");
    }

    // THE START OF THE DEPTH FIRST SEARCH METHOD
    for (i = 0; i < m1.xsize + 2; i++)
    {
        for (j = 0; j < m1.ysize + 2; j++)
        {
            if (m1.arr[i][j] != '*')
            {
                head->Unvisited = FALSE;
                head->next = head->next + 1; //MAYBE
            }
        }
    }

    head->x = m1.xstart;
    head->y = m1.ystart;
    head->Unvisited = FALSE;

    while ((isEmpty(head) == FALSE) && (m1.end == FALSE))
    {
        if ((m1.xend == head->x) && (m1.yend == head->y))
        {
            printf("The END has be found!\n");
            m1.end = TRUE;
        }
        if ((head->x + 1 && head->y) == TRUE)
        {
            push(&head, head->x + 1, head->y);
        }
        else if ((head->x - 1 && head->y) == TRUE)
        {
            push(&head, head->x - 1, head->y);
        }
        else if ((head->x && head->y + 1) == TRUE)
        {
            push(&head, head->x, head->y + 1);
        }
        else if ((head->x && head->y) == TRUE)
        {
            push(&head, head->x, head->y - 1);
        }
        else
        {
            pop(head);
        }
    }

    if (isEmpty(head) == TRUE)
    {
        printf("Maze has no solution");
        exit(0);
    }
    else
    {
        printf("%d %d", &head);
    }

    printf("%d", top(head));

    free(m1.arr);
    m1.arr = NULL;

    return 1;
}

Answer 1

这里的主要问题是你用 typedef 隐藏了指针:

typedef linked* linkedPtr;

主要是你声明

linkedPtr head = NULL;

但您从未为该变量分配/malloc空间，并且取消引用它的第一段代码调用 Undefined Behavior因为您正在取消引用空指针

// THE START OF THE DEPTH FIRST SEARCH METHOD
for (i = 0; i < m1.xsize + 2; i++)
{
    for (j = 0; j < m1.ysize + 2; j++)
    {
        if (m1.arr[i][j] != '*')
        {
            head->Unvisited = FALSE; <----------BOOOOOOOOOOOOOOM-------
            head->next = head->next + 1;
        }
    }
}

此外，调用 pop 函数时类型不匹配，请更改

pop(head);

至

pop(&head);