c - Valgrind 创建链表数组时出错(用于哈希表链接)

Question

作为概述，我正在尝试用 C 创建一个类似战舰的游戏，其中船只被放置在一个 field 上。

这是我收到的错误:

==11147== Invalid write of size 8
==11147==    at 0x400786: MakeField (battleship.c:34)
==11147==  Address 0x8 is not stack'd, malloc'd or (recently) free'd

相关代码如下:

struct piece{
    int x;
    int y;
    int direction;
    int length;
    char name;

};

struct node{
    struct piece boat;
    struct node *next;

};


struct field{
    int numBoats;
    struct node *array[numRows];
};

struct field *MakeField(void){
    struct field *f = NULL;
    struct node *temp = NULL;

    for(int i = 0; i < numRows; i++){
        f->array[i] = temp; <--- VALGRIND ERROR HERE
    }

    f->count = 0;
    return f;
}

谁能帮忙解决这个问题吗？

Answer 1

您正在解除对 NULL 指针的引用，您需要使指针指向某处并指向有效的某处，如下所示

struct field *f = malloc(sizeof(struct field));
if (f == NULL)
   return NULL;
/* ... continue your MakeField() function as it is */

不要忘记在调用函数中free(f)。

顺便说一下，valgrind正在告诉你

Address 0x8 is not stack'd, malloc'd or (recently) free'd
                           ~~~^~~~