Chained hash tables using an array of lists

This is a discussion on Chained hash tables using an array of lists within the C Programming forums, part of the General Programming Boards category; I know how to use linked lists (is that similar to an array of lists?) and I kind of understand ...

  1. #1
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    Question Chained hash tables using an array of lists

    I know how to use linked lists (is that similar to an array of lists?) and I kind of understand the concept of hash tables. But how would I implement a hash table using an array of lists. Also, how do I XOR characters?

  2. #2
    C++ Developer XSquared's Avatar
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    Try looking at Google for linked list tutorials.

    To XOR two values, use the ^ and ^= operators.

    Code:
    char a, b;
    a = 'a';
    b = 'b';
    
    a ^= b;
    b ^= a;
    a ^= b; // Now a = 'b' and b = 'a'
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

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  3. #3
    Code Goddess Prelude's Avatar
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    >But how would I implement a hash table using an array of lists.
    Play around with this simple hash table with linked list chaining. It's really very simple, you just have to see how things work.
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    
    #define TABSIZ 200
    
    struct TabRec {
        struct TabRec *next;
        char name[BUFSIZ];
    };
    
    static struct TabRec *htable[TABSIZ];
    
    unsigned hash(char *s)
    {
        unsigned h;
    
        for (h = 0; *s; s++)
            h = *s + 31 * h;
    
        return h % TABSIZ;
    }
    
    struct TabRec *find(char *name)
    {
        struct TabRec *item;
    
        for (item = htable[hash(name)]; item; item = item->next)
        {
            if (strcmp(name, item->name) == 0)
                return item;
        }
    
        return NULL;
    }
    
    struct TabRec *insert(char *name)
    {
        struct TabRec *item;
        unsigned h;
    
        if ((item = find(name)) == NULL)
        {
            /* Not found, add */
            if ((item = malloc(sizeof (*item))) == NULL)
                return NULL;
    
            strcpy(item->name, name);
    
            h = hash(name);
            item->next = htable[h];
            htable[h] = item;
        }
    
        return item;
    }
    
    int main(void)
    {
        char buf[BUFSIZ];
        struct TabRec *item;
    
        while (fgets(buf, sizeof (buf), stdin))
        {
            if (insert(buf) == NULL)
                break;
        }
    
        printf("Enter a name to find: ");
        fflush(stdout);
    
        if (fgets(buf, sizeof (buf), stdin))
        {
            if ((item = find(buf)) != NULL)
                printf("%s", item->name);
        }
    
        return 0;
    }
    My best code is written with the delete key.

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