Question

我试图创建邻接列表来表示文件＆＃34; input.txt＆＃34;中边缘列表中的图形。我知道指针如何工作的基础知识，但我有动态结构数组的问题，它由单链表组成。

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

struct list {
    int vertex;
    struct list *next;
};

void create_list(int v, struct list* **array);

int main()
{
    int i, v = 5;
    struct list *ptr, **array = (struct list **)malloc(sizeof(struct list *) * v);
    for (i = 0; i < v; i++)
        array[i] = NULL;
    array[i] = NULL;

    create_list(v, &array);

    for(i = 0; i < v; i++) {
        ptr = array[i];
        printf("%d: ", i);
        while(ptr != NULL) {
            printf(" ->%d", ptr->vertex);
            ptr = ptr->next;
        }
        printf("\n");
    }
    return 0;
}

void create_list(int v, struct list* **array)
{
    int m, n;
    struct list *ptr, *tmp;
    FILE *luki;
    luki = fopen("input.txt", "r");
    while(fscanf(luki, "%d %d\n", &m, &n) == 2) {
        tmp = (struct lista*)malloc(sizeof(struct list));
        tmp->vertex = n;
        tmp->next = NULL;
        if (*array[m] == NULL)      //Here my program crashes when m changes from 0 to 1
            *array[m] = tmp;
        else {
            ptr = array[m];
            while(ptr->next != NULL)
                ptr = ptr->next;
            ptr->next = tmp;
        }
    }
    fclose(luki);
}

你能帮我弄清楚它应该是什么样的吗？

此外，首先我在不使用指向数组的指针的情况下创建了函数：

void create_list(int v, struct list **array)

create_list(v, array);

在调试和（我使用CodeBlocks）时它的效果非常好：

0: 4 ->3 ->1
1: 2
2: 3
3:
4:

但是在正常运行程序时我得到了这个：

0:
1:
2:
3:
4:

为什么调试时的输出是正确的，如果将数组传递给函数create_list是错误的？

Answer 1

（1）#menuBackground { background:#5EA5B9; width:100%; height:50px; text-align: center; } #menuContainer { text-align: center; } /*Strip the ul of padding and list styling*/ ul { list-style-type:none; margin:0; padding:0; } /*Create a horizontal list with spacing*/ li { display:inline-block; vertical-align: top; margin-right:1px; } /*Style for menu links*/ li a { display:block; min-width:140px; height:50px; text-align:center; line-height:50px; font-family:Georgia; color:#fff; background:#5EA5B9; text-decoration:none; font-size: 1rem; } /*Hover state for top level links*/ li:hover a { color: #036; background:#fff } /*Prevent text wrapping*/ li ul li a { width:auto; min-width:100px; padding:0 20px } /*Style 'show menu' label button and hide it by default*/ .show-menu { font-family:Georgia; text-decoration:none; color:#fff; background:#5EA5B9; text-align:center; padding:16px 0; display:none; width:100%!important } /*Hide checkbox*/ input[type=checkbox] { display:none } /*Show menu when invisible checkbox is checked*/ input[type=checkbox]:checked ~ #menu { display:block; margin:0 auto } /*Responsive Styles*/ @media screen and (max-width : 760px) { /*Make dropdown links appear inline*/ ul { position:static; display:none; white-space: initial; } /*Create vertical spacing*/ li { margin-bottom:1px } /*Make all menu links full width*/ ul li,li a { width:100% } /*Display 'show menu' link*/ .show-menu { display:block } }

<div id="menuBackground">
    <div id="menuContainer">
        <label for="show-menu" class="show-menu">Show Menu</label>        <input type="checkbox" id="show-menu" role="button" />
        <ul id="menu">
            <li><a href="index.html">Home</a>
            </li>
            <li><a href="accommodations.html">Accommodations</a>
            </li>
            <li><a href="amenities.html">Amenities</a>
            </li>
             <li><a href="rates.html">Rates</a>
            </li>
             <li><a href="links.html">Links</a>
            </li>
            <li><a href="contact.html">Contact</a>
            </li>
         </ul>
    </div>
</div>

（2）void create_list(int v, struct list **array); ... create_list(v, array);

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

struct list {
    int vertex;
    struct list *next;
};

void create_list(int v, struct list **array);

int main(void) {
    int i, v = 5;
    struct list *ptr, **array = (struct list **)malloc(sizeof(struct list *) * v);
    for (i = 0; i < v; i++)
        array[i] = NULL;

    create_list(v, array);

    for(i = 0; i < v; i++) {
        ptr = array[i];
        printf("%d: ", i);
        while(ptr != NULL) {
            printf("%d", ptr->vertex);
            ptr = ptr->next;
            if(ptr)
                printf(" -> ");
        }
        printf("\n");
    }
    return 0;
}

void create_list(int v, struct list **array){
    int m, n;
    struct list *ptr, *tmp;
    FILE *luki;
    luki = fopen("input.txt", "r");
    while(fscanf(luki, "%d %d\n", &m, &n) == 2) {
        tmp = (struct list*)malloc(sizeof(struct list));
        tmp->vertex = n;
        tmp->next = NULL;
        if (array[m] == NULL)
            array[m] = tmp;
        else {
            ptr = array[m];
            while(ptr->next != NULL)
                ptr = ptr->next;
            ptr->next = tmp;
        }
    }
    fclose(luki);
}

C语言中的动态结构数组

1 个答案: