String array() in C

Discussion in 'C Programming' started by JackYee123@gmail.com, May 7, 2007.

  1. Guest

    Hey,

    I need a structure to store a string array in c, for example

    Index Content
    -------- -----------
    0 word1
    1 word2
    2
    3
    4
    5
    , May 7, 2007
    #1
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  2. Guest

    Here is the compelte message

    Hi,

    I need a structure to store a string array in c, for example

    Index Content
    -------- -----------
    0 word1
    1 word2
    2 word3
    3 word4
    4 word5
    5 word6
    --------------------

    I was thinking to use char**, but I don't want to use double pointer,
    if there an easy way to get around this?

    Thanks.
    , May 7, 2007
    #2
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  3. <> wrote in message
    news:...
    > Here is the compelte message
    >
    > Hi,
    >
    > I need a structure to store a string array in c, for example
    >
    > Index Content
    > -------- -----------
    > 0 word1
    > 1 word2
    > 2 word3
    > 3 word4
    > 4 word5
    > 5 word6
    > --------------------
    >
    > I was thinking to use char**, but I don't want to use double pointer,
    > if there an easy way to get around this?
    >

    No. You can declare an array of pointers, but really the array is just a
    char ** dressed up with different syntax.
    If don't know how many string you need at run time

    char **list;
    int N;

    and malloc() is the way to go.
    If you do

    char *list[N];

    is OK.

    However you very rarely need raw tables of strings. Usually the string is
    tied to something. So
    struct mydata
    {
    char *word;
    int value;
    double value2;
    };

    where value and value2 are arbitrary things, eg counts, associated with each
    "word", is more common.
    --
    Free games and programming goodies.
    http://www.personal.leeds.ac.uk/~bgy1mm
    Malcolm McLean, May 7, 2007
    #3
  4. Default User Guest

    wrote:

    > Here is the compelte message
    >
    > Hi,
    >
    > I need a structure to store a string array in c, for example
    >
    > Index Content
    > -------- -----------
    > 0 word1
    > 1 word2
    > 2 word3
    > 3 word4
    > 4 word5
    > 5 word6
    > --------------------
    >
    > I was thinking to use char**, but I don't want to use double pointer,
    > if there an easy way to get around this?


    Is your number of strings fixed, or variable?




    Brian
    Default User, May 7, 2007
    #4
  5. Eric Sosman Guest

    wrote On 05/07/07 13:31,:
    > Here is the compelte message
    >
    > Hi,
    >
    > I need a structure to store a string array in c, for example
    >
    > Index Content
    > -------- -----------
    > 0 word1
    > 1 word2
    > 2 word3
    > 3 word4
    > 4 word5
    > 5 word6
    > --------------------
    >
    > I was thinking to use char**, but I don't want to use double pointer,
    > if there an easy way to get around this?


    There are several approaches with different advantages
    and disadvantages. You haven't specified your needs very
    precisely, so I'll just sketch out a few methods. Note that
    these are NOT equivalent!


    /* Fixed-length array of fixed-length words (any
    * short words are followed by extra '\0' bytes
    * to a total size of six). Array elements are
    * modifiable, but no word can grow beyond five
    * payload characters.
    */
    char words[][5+1] = { "word1", ..., "word6", };


    /* Fixed-length array of pointers to words of
    * arbitrary length. The pointers can be changed
    * to point at different words, but the original
    * word data cannot be changes.
    */
    char *words[] = { "word1", ..., "word6", };


    /* Fixed-length array of pointers to words of
    * arbitrary length. Both the pointers and the
    * words can be changed, but the original words
    * cannot be lengthened in place.
    */
    char word1[] = "word1";
    ...
    char word6[] = "word6";
    char *words[] = { word1, ..., word6, };


    /* Dynamically allocated "array" of fixed-length
    * words. Array elements are modifiable, but the
    * words themselves cannot be lengthened. The
    * typedef is for clarity, and can be eliminated.
    */
    typedef char Word[5+1];
    Word *words = malloc(N * sizeof *words);
    if (words != NULL) {
    strcpy (words[0], "word1");
    ...
    strcpy (words[5], "word6");
    }


    /* Dynamically-allocated "array" of pointers to
    * dynamically-allocated words. Everything is
    * modifiable, replaceable, extensible, all-
    * singing, all-dancing, and carbon-neutral.
    */
    char **words = malloc(N * sizeof *words);
    if (words != NULL) {
    words[0] = malloc(sizeof "word1");
    if (words[0] != NULL)
    strcpy (words[0], "word1");
    ...
    /* A different way to calculate the size: */
    words[5] = malloc(strlen("word6") + 1);
    if (words[5] != NULL)
    strcpy (words[5], "word6");
    }

    --
    Eric Sosman, May 7, 2007
    #5
  6. wrote:
    > Hey,
    >
    > I need a structure to store a string array in c, for example
    >
    > Index Content
    > -------- -----------
    > 0 word1
    > 1 word2
    > 2
    > 3
    > 4
    > 5
    >


    char array_of_strings[6][6] = {"word1", "word2"}; /* in your restricted
    chase. The strings are modifiable. */

    char *array_of_strings[] = {"word1", "word2"}; /* More generally, but
    the strings must be copied elsewhere if you want to use modified forms
    of them, although the pointers can be modified. */

    char *array_of_strings[6] = {"word1", "word2"}; /* If you must have six
    strings, and string literals are not a problem. */
    Martin Ambuhl, May 7, 2007
    #6
  7. Malcolm McLean wrote:
    >
    > <> wrote in message
    > news:...

    [...]
    >> I was thinking to use char**, but I don't want to use double pointer,
    >> if there an easy way to get around this?
    >>

    > No. You can declare an array of pointers, but really the array is just a
    > char ** dressed up with different syntax.


    This is wrong. Malcolm has been around long enough to know that a
    pointer is not an array, and a pointer to a pointer is not the same as
    an array of pointers. And he has been around long enough to know that
    lying to seekers after knowledge is not welcome here.
    Martin Ambuhl, May 7, 2007
    #7
  8. Richard Guest

    Martin Ambuhl <> writes:

    > wrote:
    >> Hey,
    >>
    >> I need a structure to store a string array in c, for example
    >>
    >> Index Content
    >> -------- -----------
    >> 0 word1
    >> 1 word2
    >> 2
    >> 3
    >> 4
    >> 5
    >>

    >
    > char array_of_strings[6][6] = {"word1", "word2"}; /* in your
    > restricted chase. The strings are modifiable. */


    That is disgusting code.

    >
    > char *array_of_strings[] = {"word1", "word2"}; /* More generally, but
    > the strings must be copied elsewhere if you want to use modified forms
    > of them, although the pointers can be modified. */


    Which pointers? No "pointers" can be modified.

    >
    > char *array_of_strings[6] = {"word1", "word2"}; /* If you must have
    > six strings, and string literals are not a problem. */
    >


    Misleading. If you are going to use "six" then specify all the strings.


    --
    Richard, May 7, 2007
    #8
  9. Richard <> wrote:
    > Martin Ambuhl <> writes:
    > > wrote:
    > >> I need a structure to store a string array in c, for example
    > >>
    > >> Index Content
    > >> -------- -----------
    > >> 0 word1
    > >> 1 word2
    > >> 2
    > >> 3
    > >> 4
    > >> 5
    > >>

    > >
    > > char array_of_strings[6][6] = {"word1", "word2"}; /* in your
    > > restricted chase. The strings are modifiable. */


    > That is disgusting code.


    Why? Perhaps an array of 6 strings, each long enough to hold 6 chars
    is exactly what the OP needs. The problem is that underspecified that
    this could be just the correct solution. But since that's not clear,
    Mr. Ambuhl continued with:

    > > char *array_of_strings[] = {"word1", "word2"}; /* More generally, but
    > > the strings must be copied elsewhere if you want to use modified forms
    > > of them, although the pointers can be modified. */


    > Which pointers? No "pointers" can be modified.


    What are you talking about?

    > > char *array_of_strings[] = {"word1", "word2"};


    defines an array of two pointers to char arrays and those pointers
    can be modified, i.e. made to point to other strings (or char
    arrays to be precise).

    > > char *array_of_strings[6] = {"word1", "word2"}; /* If you must have
    > > six strings, and string literals are not a problem. */


    > Misleading. If you are going to use "six" then specify all the strings.


    Which would you use, going by what the OP wrote? Invent some?

    Regards, Jens
    --
    \ Jens Thoms Toerring ___
    \__________________________ http://toerring.de
    Jens Thoms Toerring, May 7, 2007
    #9
  10. Old Wolf Guest

    On May 8, 7:31 am, Martin Ambuhl <> wrote:
    > Malcolm McLean wrote:
    > > [rubbish confusing arrays and pointers]

    >
    > This is wrong. Malcolm has been around long enough to know that a
    > pointer is not an array, and a pointer to a pointer is not the same as
    > an array of pointers. And he has been around long enough to know that
    > lying to seekers after knowledge is not welcome here.


    Are you sure he is lying? Perhaps he is just mistaken. With the
    the number of wrong posts he makes each day (even more than
    I do!), it would be quite a tour-de-force of trollage.
    Old Wolf, May 7, 2007
    #10
  11. In article <-berlin.de>,
    Jens Thoms Toerring <> wrote:

    >> > char *array_of_strings[6] = {"word1", "word2"}; /* If you must have
    >> > six strings, and string literals are not a problem. */

    >
    >> Misleading. If you are going to use "six" then specify all the strings.

    >
    >Which would you use, going by what the OP wrote? Invent some?


    It appears that the OP inadvertently sent the article before he finished
    it. He followed up with a complete version that included six strings.

    -- Richard
    --
    "Consideration shall be given to the need for as many as 32 characters
    in some alphabets" - X3.4, 1963.
    Richard Tobin, May 7, 2007
    #11
  12. Richard wrote:
    > Martin Ambuhl <> writes:
    >
    >> wrote:
    >>> Hey,
    >>>
    >>> I need a structure to store a string array in c, for example
    >>>
    >>> Index Content
    >>> -------- -----------
    >>> 0 word1
    >>> 1 word2
    >>> 2
    >>> 3
    >>> 4
    >>> 5
    >>>

    >> char array_of_strings[6][6] = {"word1", "word2"}; /* in your
    >> restricted chase. The strings are modifiable. */

    >
    > That is disgusting code.


    Perhaps you could explain what aesthetic criterion leads you to such an
    idiosyncratic claim.

    >> char *array_of_strings[] = {"word1", "word2"}; /* More generally, but
    >> the strings must be copied elsewhere if you want to use modified forms
    >> of them, although the pointers can be modified. */

    >
    > Which pointers? No "pointers" can be modified.


    array_of_strings is an array of pointer, all of which can be modified.
    Perhaps you could explain what strange language standard leads you to
    such an idiosyncratic claim.


    >
    >> char *array_of_strings[6] = {"word1", "word2"}; /* If you must have
    >> six strings, and string literals are not a problem. */
    >>

    >
    > Misleading. If you are going to use "six" then specify all the strings.


    If you knew your ass from a whole in the ground, you would know
    a) the initialization is complete and
    b) contains all the information in the original poster's message. To
    pretend that one "knows" what the other strings are is a misleading
    claim of mind-reading; to pretend that the initialization requires 6
    explict initialisers is misleading and untrue.

    Perhaps you could explain what leads you to such an absurd and
    idiosyncratic claim.
    Martin Ambuhl, May 7, 2007
    #12
  13. Joe Wright Guest

    Old Wolf wrote:
    > On May 8, 7:31 am, Martin Ambuhl <> wrote:
    >> Malcolm McLean wrote:
    >>> [rubbish confusing arrays and pointers]

    >> This is wrong. Malcolm has been around long enough to know that a
    >> pointer is not an array, and a pointer to a pointer is not the same as
    >> an array of pointers. And he has been around long enough to know that
    >> lying to seekers after knowledge is not welcome here.

    >
    > Are you sure he is lying? Perhaps he is just mistaken. With the
    > the number of wrong posts he makes each day (even more than
    > I do!), it would be quite a tour-de-force of trollage.
    >

    I think you're on to something here Wolf. :)

    --
    Joe Wright
    "Everything should be made as simple as possible, but not simpler."
    --- Albert Einstein ---
    Joe Wright, May 8, 2007
    #13
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