C-指向结构体的指针的指针

Question

I have a linked list with a hash table in each node. The hash table is implemented by an array of pointers to structs. The whole management of this is made by a global static pointer to the linked list.

• I changed a little bit the question! Now the question is more focused.

in the lookup and insert function to make the code shorter I assign

temp = cur_table->symbols_table[entry];

but I see that temp gets NULL all the time. I can't understand why is that happens?

The code is below in 3 modules. Thank you in ahead.

symbols.h file:

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

#define TABLE_SIZE 26

typedef struct symbol_node
{
  char* name;
  int type;
  int role;

  struct symbol_node* next;

} symbol_node;

typedef struct table_node
{
  struct symbol_node* symbols_table[TABLE_SIZE];
  struct table_node* prev;
  struct table_node* next;

} table_node;


static struct table_node* cur_table;

//functions declarations:
void init_table();
int hash_function(char* id);
symbol_node* lookup(char* id_name);
symbol_node* insert(char* id_name);
// debug
void printtable();

symbols.c

 void init_table() // creates the first node                                                                                                                                                                        
 {
  int i = 0;
  cur_table = NULL;

  cur_table = (table_node*)malloc(sizeof(table_node));

  cur_table->prev = NULL;
  cur_table->next = NULL;

  for(i=0; i < TABLE_SIZE; i++)
    {
      cur_table->symbols_table[i] = NULL;
    }
}

symbol_node* lookup(char* id_name)  // returns null if the id name not found                                                                                                                                       
{
  symbol_node* result = NULL;
  symbol_node* temp = NULL;
  int entry = atoi(id_name);

  temp = cur_table->symbols_table[entry];

  while(temp != NULL)
    {
      if( strcmp( id_name, temp->name ) == 0 )
    {
          result = temp;
          break;
        }
      else
        temp = temp->next;
    }

  return result;
}


symbol_node* insert(char* id_name)
{
  symbol_node* result = NULL;
  symbol_node* temp = NULL;
  int index = -1;

  if(lookup(id_name)==NULL)
    {
      index = atoi(id_name);
      temp = cur_table->symbols_table[index];

      while(temp!=NULL)
        {
          temp = temp->next;
        }

      temp = (symbol_node*)malloc(sizeof(symbol_node));
      temp->next = NULL;
      temp->name = id_name;
      // TODO: other params                                                                                                                                                                                        

      result = temp;
    }

  return result;
}
void printtable()
{
int i=0;

for(i=0; i<TABLE_SIZE; i++)
{
    if(cur_table->symbols_table[i]==NULL)
        printf("NULL at index %d\n",i);
    else
        printf("There are something\n");
}
}

main.c

void main()
{
int i=0;
symbol_node* t = NULL;
symbol_node* tt = NULL;
init_table();

t = insert("markhit");
t = insert("mark");

tt = lookup("mark");

printtable();

_getch();

  free(t);
  free(tt);
  free(cur_table);
}

Answer 1

avoid memory allocation [`malloc'] statically. try it

cur_table = new table_node;

for statically allocated memory, you can not set your value for memory reason. when you are inserting it is not reallocating your cur_table