trying to make a hash table......trouble w/ memory?

This is a discussion on trying to make a hash table......trouble w/ memory? within the C Programming forums, part of the General Programming Boards category; For now I am just trying to implement a hash table and a simplified version to see it work. Each ...

  1. #1
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    trying to make a hash table......trouble w/ memory?

    For now I am just trying to implement a hash table and a simplified version to see it work. Each entry has a key and a value and a pointer (in case of collisions it is a linked list)
    Then the hash table is an array of those entries. I started initializing the table and printing it out just to make sure things are working. I don't think I'm using malloc correctly for array of structures because I keep getting segmentation fault core dump as an error.
    help

    Code:
    #define TABLE_SIZE ((int) 10)
    struct entryhash
    {
       int key; //order of nodes will be string later to match other stuff
       double num;  //entry is another structure, replace with double for now?
       struct entryhash * next;  //linked structure in case of collision
    };
    
    typedef struct entryhash hash_item;
    
    void print_table (hash_item **head,int tablelen){
      int i;
      hash_item *curr;
      for (i=0; i <tablelen; i++){
          curr=head[i];
          printf("%d\n", curr->key);
          //printf("%lf\n", curr->num);
       }
    }
    
    int main(){
       hash_item ** newhash;
       newhash = (hash_item **)malloc(sizeof(hash_item*) * TABLE_SIZE);
       //initialize everything to null?
       int i;
       for (i=0; i<TABLE_SIZE; i++){
          newhash[i]->key= -1;
          newhash[i]->next=NULL;
       }
       print_table(newhash, TABLE_SIZE);
       //add entries 
       //add_hash_el( &newhash, 9,2.5);
       return 0;
    }

  2. #2
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    Allocate storage for each of the hash_item objects that the array of pointers newhash points to before initializing them.

  3. #3
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    do you mean going through a loop and assigning
    newhash[i] = (hash_item *)malloc(sizeof(hash_item));
    ?

  4. #4
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    Yep! at the top the the loop where the members of hash_item are being initialized to null.

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