size of an array poited by array element

This is a discussion on size of an array poited by array element within the C Programming forums, part of the General Programming Boards category; hi i have a problem with this : Code: char *aa[] = { "a1","a2","a3" }; char *ab[] = { "b1","b2" ...

  1. #1
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    size of an array poited by array element

    hi i have a problem with this :

    Code:
    char *aa[] = { "a1","a2","a3" };
    char *ab[] = { "b1","b2" };
    char *ac[] = { "c1","c2","c3","c4" };
    
    char **pabc[] = { aa, ab, ac };
    i want to call

    Code:
    int n = sizeof (pabc[0])/sizeof(char*);
    to get the size of array aa.
    i think i'm doing it the wrong way

    thanks for help

  2. #2
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    No,You can't. since the type of pabc[0] is pointer to pointer to char.
    sizeof(pabc[0]) = sizeof(char**)

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    no way

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    By size of array aa do you mean the number of bytes it takes up in storage or the number of elements it contains? The formula you're using looks like an alteration of a common way to get the number of elements in an array. If the scope you're in can "see" the definition of aa, you can do:
    Code:
    int n_elements = sizeof(aa) / sizeof(aa[0]);
    int n_bytes = sizeof(aa);
    If you're in some scope that can't see the definition, you're out of luck. Declare aa to be some fixed size, like so:
    Code:
    #define AA_LEN 3
    char *aa[AA_LEN] = {"a1", "a2", "a3"};
    or use a sentinel value (null terminate it) and write a function to get the length:
    Code:
    char *aa[] = {"a1", "a2", "a3", NULL};
    int strv_len(char *aa[])
    {
        int i;
        for (i = 0; aa[i]; i++);
        return i;
    }

  5. #5
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    Quote Originally Posted by anduril462 View Post
    By size of array aa do you mean the number of bytes it takes up in storage or the number of elements it contains?
    yes, i want to check the number of elements and thank you for your reply.

  6. #6
    ATH0 quzah's Avatar
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    Quote Originally Posted by mitofik View Post
    yes, i want to check the number of elements and thank you for your reply.
    You have to keep track of that on your own.


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

  7. #7
    zfk
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    i don't know what your means ,but you can try fthe code as following
    Code:
    int n = sizeof(pabc) / sizeof(pabc[0]);

    it get the number of a array .

  8. #8
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    zfk: you should actually read this thread to avoid giving an incorrect reply.
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