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structures and pointers and members

This is a discussion on structures and pointers and members within the C Programming forums, part of the General Programming Boards category; Code: struct wordPair { char* englishWord; char* foreignWord; }; struct dictionary { struct wordPair ** data; int nbwords; int size; ...

  1. #1
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    structures and pointers and members

    Code:
    struct wordPair {
           char* englishWord;
           char* foreignWord;
    };
    
    struct dictionary {
           struct wordPair ** data;
           int nbwords;
           int size;
    } *d;
    how would I access members englishWord and foreignWord through *d? I've tried:

    d->data->englishWord;
    d->data->foreignWord;

    but i get errors saying:

    error C2223: left of '->englishWord' must point to struct/union
    error C2223: left of '->foreignWord' must point to struct/union

  2. #2
    ATH0 quzah's Avatar
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    Code:
    struct dictionary {
           struct wordPair ** data;
           int nbwords;
           int size;
    } *d;
    That's a pointer to a pointer. I doubt that's what you want. But on the off chance it is, you should familiarize yourself with parenthesis. Or just pretend it's an array:
    Code:
    d->data[ X ]->englishWord;
    Quzah.
    Hope is the first step on the road to disappointment.

  3. #3
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    Make things easy - use typedef to create pointer types to your structures - then you don't get hung up in pointer notation (as much):

    Code:
    #include <stdio.h>
    #include <string.h>
    #include <stdlib.h>
    
    typedef struct wordPair {
        char *englishWord;
        char *foreignWord;
    } WordPair;
    
    typedef WordPair *WordPairPtr;
    
    typedef struct dictionary {
        WordPairPtr data;
        int nbwords;
        int size;
    } Dictionary;
    
    typedef Dictionary *DictionaryPtr;
    
    int main( void )
    {
        /* allocate one dictionary structure */
        DictionaryPtr newDictionary = ( DictionaryPtr )malloc( sizeof( Dictionary ) );
    
        /* allocate word pair structure */
        newDictionary->data = ( WordPairPtr )malloc( sizeof( WordPair ) );
    
        /* initialize our new dictionary structure */
        newDictionary->data->englishWord = ( char * )calloc( 10, sizeof( char ) );
        strcpy( newDictionary->data->englishWord, "Hello" );
    
        newDictionary->data->foreignWord = ( char * )calloc( 10, sizeof( char ) );
        strcpy( newDictionary->data->foreignWord, "Bonjour" );
    
        newDictionary->nbwords = 1;
        newDictionary->size    = 1;
    
    
        /* use it */
        printf( "\"%s\" translates to \"%s\"\n",
                newDictionary->data->englishWord,
                newDictionary->data->foreignWord );
    
    
        /* free the memory - note we need to do a deep free */
        free( newDictionary->data->englishWord );
        free( newDictionary->data->foreignWord );
        free( newDictionary->data );
        free( newDictionary );
    
        return EXIT_SUCCESS;
    }
    Last edited by kmess; 04-18-2011 at 10:58 PM.

  4. #4
    ATH0 quzah's Avatar
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    Quote Originally Posted by kmess View Post
    Make things easy - use typedef to create pointer types to your structures
    People who typedef pointers need to be bludgeoned.

    Quzah.
    Salem likes this.
    Hope is the first step on the road to disappointment.

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