Extracting strings from a buffer

This is a discussion on Extracting strings from a buffer within the C Programming forums, part of the General Programming Boards category; Hi. I am trying to extract a series of strings that are put together in a buffer like this: David_Smith__monkey___555-1435__555-1323__test.com_ ...

  1. #1
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    Extracting strings from a buffer

    Hi.

    I am trying to extract a series of strings that are put together in a buffer like this:

    David_Smith__monkey___555-1435__555-1323__test.com_

    one _ equals one VTAB.

    The strings should be inserted in a struct, the struct looks like this:
    struct Contact {
    char fname[50];
    char sname[50];
    char nmame[50];
    char home[50];
    char next[50];
    char temp[50];
    };

    So, Devid should go in fname, Smith in sname, nname should be skipped since there is nothing between the two TABS, etc.

    I am stuck so any help would be very appreciated.
    /MoonSire

  2. #2
    Code Goddess Prelude's Avatar
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    This looks like a job for sscanf. Then again, you said that empty fields are allowed, so it may be more convenient to manually parse or take advantage of some of the string searching functions in string.h. What have you tried so far?
    My best code is written with the delete key.

  3. #3
    Registered User Micko's Avatar
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    How about this:
    Code:
    ... CENSORED
     
        char  *sep = strtok(buff, DELIM);
    
        if (sep != NULL)
        {
          strcpy(ct.fname, sep);
          sep = strtok(NULL, DELIM);
         
    ... CENSORED
    Last edited by Micko; 07-28-2006 at 07:56 AM.
    Gotta love the "please fix this for me, but I'm not going to tell you which functions we're allowed to use" posts.
    It's like teaching people to walk by first breaking their legs - muppet teachers! - Salem

  4. #4
    Just Lurking Dave_Sinkula's Avatar
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    Quote Originally Posted by MoonSire
    David_Smith__monkey___555-1435__555-1323__test.com_

    one _ equals one VTAB.

    [...]

    So, Devid should go in fname, Smith in sname, nname should be skipped since there is nothing between the two TABS, etc.
    Quote Originally Posted by Micko
    How about this:
    Code:
        char  *sep = strtok(buff, DELIM);
        if (sep != NULL)
        {
          strcpy(ct.fname, sep);
          sep = strtok(NULL, DELIM);
    strtok doesn't handle multiple consecutive delimiters in the desired fashion.

    Perhaps one of these instead:
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

  5. #5
    ATH0 quzah's Avatar
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    You'll also need a function to subsitute the occurrence of 'a' with the letter 'e'.


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

  6. #6
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    On the link for using strcspn Part 1, I didnt think the following line was legal c code

    Code:
    printf("line %d:\n", ++k);
    Maybe I mis-understood the concept of a sequence point from the c faq.
    http://c-faq.com/expr/seqpoints.html

    and
    http://c-faq.com/expr/evalorder2.html

  7. #7
    ... kermit's Avatar
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    What's wrong with it? k is only being evaluated once, so there is no ambiguity about the expression. If k was used twice in the expression, then you might have trouble. In this case there is no trouble.

  8. #8
    Registered User Micko's Avatar
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    Quote Originally Posted by Dave_Sinkula
    strtok doesn't handle multiple consecutive delimiters in the desired fashion.
    You're right, I didn't pay attention
    Gotta love the "please fix this for me, but I'm not going to tell you which functions we're allowed to use" posts.
    It's like teaching people to walk by first breaking their legs - muppet teachers! - Salem

  9. #9
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    Thanks guys!

    I completely overlooked›sscanf so my solution was extracting each char from the buffer and inserting it into the struct with an array of pointers to each variable in the struct

  10. #10
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    I tried using this one:

    #include <stdio.h>
    ..
    int main(void)
    {
    const char line[] = "2004/12/03 12:01:59;info1;info2;info3";
    const char *ptr = line;
    char field [ 32 ];
    int n;
    while ( sscanf(ptr, "%31[^;]%n", field, &n) == 1 )
    {
    printf("field = \"%s\"\n", field);
    ptr += n; /* advance the pointer by the number of characters read */
    if ( *ptr != ';' )
    {
    break; /* didn't find an expected delimiter, done? */
    }
    ++ptr; /* skip the delimiter */
    }
    return 0;
    }

    But modified it with a "[^\t]" instead of the "[^;] and changed the line to "David\tapa\tkorv\tfillefjong\t104510\t\tnisse ";
    But the only output I get then is
    field = "David"

    I looked in man page for sscanf and the way I understand it nothing else should need to be changed...Am I wrong?

  11. #11
    ATH0 quzah's Avatar
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    Aside from not using code tags...

    Shouldn't you also change the break condition?


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

  12. #12
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    well well, i'm off to bed

    thanks quzah!

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