Extracting info from string

This is a discussion on Extracting info from string within the C Programming forums, part of the General Programming Boards category; I have a string containing '|' delimiters which is like : Testing|1|2|3|4 What I want to do is to extract ...

  1. #1
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    Extracting info from string

    I have a string containing '|' delimiters which is like :

    Testing|1|2|3|4

    What I want to do is to extract the data in between the delimiters respectively.
    The problem is i do not know how many '|' are in between...

    and assuming i do not know how many delimiters there are, how do i detect the number of '|' or does anyone know a way around this?
    Only by the cross are you saved...

  2. #2
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    You can use strtok() for the same. Look up the man pages.

    Anoop.

  3. #3
    Code Goddess Prelude's Avatar
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    strtok is okay as long as you don't have to worry about concurrency or nested calls. In those cases strtok will fail miserably. Some libraries have a strtok_r that is reentrant, but I've found that it's easier just to follow in the footsteps of argc and argv:
    Code:
    /* Warning: Ugly code follows. Sorry, written in haste. */
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    
    int makeargv(char *plist, char ***argv, char *delim)
    {
        char   *pos = plist;
        size_t dlen = strlen(delim);
        int    argc = 0;
        int    i;
    
        /* Count args */
        while ((pos = strstr(pos, delim)) != NULL) {
            argc++;
            pos += dlen;
        }
    
        if ((*argv = malloc((argc + 1) * sizeof **argv)) == NULL)
            return -1;
    
        for (i = 0, pos = plist; i < argc; i++, plist = pos + dlen) {
            pos = strstr(plist, delim);
    
            if (((*argv)[i] = calloc((pos - plist) + 1, sizeof (*argv)[i])) == NULL) {
                while (--i >= 0)
                    free((*argv)[i]);
                free(*argv);
    
                return -1;
            }
    
            strncpy((*argv)[i], plist, pos - plist);
        }
    
        /* Last token */
        if (((*argv)[i] = calloc(strlen(plist) + 1, sizeof (*argv)[i])) == NULL) {
            while (--i >= 0)
                free((*argv)[i]);
            free(*argv);
    
            return -1;
        }
    
        strcpy((*argv)[i++], plist);
        (*argv)[i] = NULL;
    
        return argc + 1;
    }
    
    int main(void)
    {
        char **argv;
        char test[] = "Testing|1|2|3|4";
        int  argc;
        int  i;
    
        /* Using makeargv */
        if ((argc = makeargv(test, &argv, "|")) != -1) {
            for (i = 0; i < argc; i++) {
                puts(argv[i]);
                free(argv[i]);
            }
    
            free(argv);
        }
    
        return 0;
    }
    My best code is written with the delete key.

  4. #4
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    oops, entered wrong board, message deleted. Sorry.
    Last edited by elad; 08-25-2003 at 10:24 AM.

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