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This is a discussion on burchasergin within the C Programming forums, part of the General Programming Boards category; for example i enter an string lenght is n.how can i take space from memory for that string for example ...

  1. #1
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    Post memry allocation

    for example i enter an string lenght is n.how can i take space from memory for that string
    for example my array is word[32] but my name has 4 characters
    the rest of this array dont be used. how can i prevent this?
    Last edited by condorx; 05-24-2002 at 02:28 PM.

  2. #2
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    By allocating memory dynamically.

    Code:
    char *word;
    int length;
    
    length = .... <determine length here or get it from somewhere>..;
    
    /* Create a dynamic array */
    word = malloc (sizeof (char) * length);
    
    ..... <do some stuff with word> ...
    
    /* Release the allocated memory */
    free (word);
    If I remember well, C99 supports dynamical arrays in this way:

    Code:
    void function (int length)
    {
        char word [length];
         
        ... <some stuff> ...
    }

  3. #3
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    By the way, what is C99?
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  4. #4
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    C99 is the code of the latest C standard, ISO/IEC 9899:1999.

  5. #5
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    Does VC++.NET support this standard?
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  6. #6
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    They claim they do but no compiler conforms 100%

  7. #7
    ATH0 quzah's Avatar
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    Originally posted by Shiro
    By allocating memory dynamically.

    Code:
    char *word;
    int length;
    
    length = .... <determine length here or get it from somewhere>..;
    
    /* Create a dynamic array */
    word = malloc (sizeof (char) * length);
    
    ..... <do some stuff with word> ...
    
    /* Release the allocated memory */
    free (word);
    Close, but no cigar. This is a "Bad Thing(TM)". You fail to allocate enough space for the null terminator (unless you've included that in your "lenght" count).

    word = malloc( sizeof(char) * (length + 1) );
    word[length] = '\0';

    Now it's safe to use. (Actually you may want to memset it, but that's optional.)

    Quzah.
    Hope is the first step on the road to disappointment.

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