Freeing a double pointer from a struct

问题

I have a problem with my delete_table function. So i have 2 structs

struct _entry_ {
    int key;
    int data;
    struct _entry_* next;
    struct _entry_* prev;
};
typedef struct _entry_ entry;

struct _table_ {
    entry** entries;
    int size;
};
typedef struct _table_ table;

I initialise my table with calloc.

void table_init(table* ht, int initial_size) {
    ht->entries = (entry**)calloc(initial_size, sizeof(entry*));
    if (ht->entries) {
        ht->size = initial_size;
    }
}

Now my free function that i wrote

void table_destroy(htable* ht) {

    entry *el, *temp;
    int i;
    for(i = 0; i < ht->size; i++) {
      el = ht->entries[i];
      while(el != NULL){
        temp = el;
        el = el->next;
        free(temp);
      }
      free(ht->entries[i]);
    }
    free(ht); // <- don't know do i need this.
}

When i test it with valgrind i got this error

==13560== Invalid free() / delete / delete[] / realloc()
==13560==    at 0x4C2BDEC: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==13560==    by 0x400783: htable_destroy (htable.c:46)
==13560==    by 0x400A24: main (main.c:25)
==13560==  Address 0xffefffae0 is on thread 1's stack
==13560==  in frame #2, created by main (main.c:7)

Any help would be great, thank you for your time!

回答1:

void table_destroy(htable* ht) {

    entry *del;
    int i;
    for(i = 0; i < ht->size; i++) {
      while( (del = ht->entries[i]) ) {
        ht->entries[i] = del->next;
        free(del);
      }
    }
    free(ht->entries);
    free(ht); 
}

来源：https://stackoverflow.com/questions/43125266/freeing-a-double-pointer-from-a-struct