使用递归反向打印链表数据时出现分段错误

Question

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

typedef struct node {
        char c;
        struct node *next;
} node_t;

node_t *head = NULL;

void insert_list(node_t *node)
{
    static node_t *temp = NULL;
    if (!head) {
        head = node;
        //temp = node;
    }
    else {
        temp->next = node;
    }
    temp = node;

}

void create_list(char c)
{
    node_t *temp = NULL;
    temp = malloc(sizeof(node_t));
    if (temp) {
        temp->c = c;
        temp->next = NULL;
        insert_list(temp);
    }
    else
        return;
}

void print_list_reversely(node_t *temp)
{
    if (!temp)
        return;
    //print_list_reversely(temp->next); /* Working piece */
    temp = temp->next; /* This and next line together*/
    print_list_reversely(temp); /* Causing SEGFAULT */
    printf("data is %c\n", temp->c);
    return;
}

int main()
{
    create_list('a');   
    create_list('b');   
    create_list('c');
    print_list_reversely(head);
    return 0;
}

Breakpoint 4, print_list_reversely (temp=0x0) at create.c:40
40      if (!temp)
(gdb) p temp
$5 = (node_t *) 0x0
(gdb) n
41          return;
(gdb) n
47  }
(gdb) n
print_list_reversely (temp=0x602050) at create.c:45
45      printf("data is %c\n", temp->c);

Breakpoint 4, print_list_reversely (temp=0x0) at create.c:40
40      if (!temp)
(gdb) p temp
$3 = (node_t *) 0x0
(gdb) n
41          return;
(gdb) n
47  }
(gdb) 
print_list_reversely (temp=0x0) at create.c:45
45      printf("data is %c\n", temp->c);

Answer 1

认为您处于最后一个节点。

//temp = temp->next; /* This and next line together*/
//print_list_reversely(temp); /* Causing SEGFAULT */
printf("data is %c\n", temp->c);

您将TMP赋给null，并尝试打印它，导致null指针取消引用。

我认为你有以下列表

1->2->NULL

print_list_reversely(1)
           tmp = [2]
                 --->      print_list_reversely(2)
                           tmp = [NULL]
                                          --->      print_list_reversely(NULL)
                                                    return;
                           print(null->c) //Seg fault