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Full Discussion: Results Of A Variable Into An Array Using C Language
Top Forums Programming Results Of A Variable Into An Array Using C Language Post 302929345 by Corona688 on Friday 19th of December 2014 04:36:37 PM
Old 12-19-2014
C does not change what variables do depending on their type, or do anything for you when you ask it to convert one type to another. At best, it will ball it up and cram it through the mail slot, i.e. take you completely literally rather than doing the extra work you wanted.

So, if you want the string to be split, you're going to have to tell it to split it.

strtok is fairly good at doing that. It breaks strings apart on a list of letters, any letter in the list is considered a separator. (I add \n to remove newlines from the end while its at it.)

Two caveats:
  1. It modifies buf. For example, the line a:b:c:d:e\n would become a\0b\0c\0d\0e\0. So you can't call it on anything you can't modify, i.e. strtok("a:b:c:d:e", ":"); would crash.
  2. It returns pointers to things inside buf. Every time you overwrite buf[], i.e. every time you call fgets(), all the pointers strtok() gave you last time will point anywhere or nowhere.

Code:
int main()
{
        char buf[512];
        FILE *fp=fopen("/etc/passwd", "r");

        while(fgets(fp, 512, stdin) != NULL)
        {
                char *tok[64], ntok=1;

                tok[0]=strtok(buf, ":\n");
                // strtok() will keep returning more strings until
                // it runs out and returns NULL.
                tok[ntok]=strtok(NULL, ":\n"); 

                while(tok[ntok] != NULL) tok[++ntok]=strtok(NULL, ":\n");

                if(strcmp(tok[0], "bigbadwolf") == 0) puts(tok[0]);
        }
        fclose(fp);
}

Last edited by Corona688; 12-19-2014 at 05:48 PM..
These 2 Users Gave Thanks to Corona688 For This Post:
jim mcnamara metallica1973
 

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LEARN ABOUT DEBIAN

xsil2graphics

XSIL2GRAPHICS(1)					User Contributed Perl Documentation					  XSIL2GRAPHICS(1)

NAME

       xsil2graphics - generate scripts to load xsil output data files

SYNOPSIS

       xsil2graphics [options] <xsil_file>

DESCRIPTION

       Utility program bundled with xmds, used to generate scripts that load simulation output data into either matlab (http://www.mathworks.com)
       or scilab (http://www.scilab.org), which are then used to manipulate the results further if necessary and then to present the results
       graphically.

       Matlab

       To generate a matlab m-file, from the xsil file data_file.xsil use the command:

       bash$ xsil2graphics data_file.xsil

       or

       bash$ xsil2graphics --matlab data_file.xsil

       Then at the matlab command prompt:

       >> data_file

       Scilab

       To generate a scilab script file, from the xsil file data_file.xsil use the command:

       bash$ xsil2graphics --scilab data_file.xsil

       Then at the scilab command prompt:

       --> exec('data_file.sci')

OPTIONS

       -m, --matlab generate matlab m-file script to load data from the xsil data file (the default option)

       -s, -scilab generate scilab script file to load data from the xsil data file

       -o, --outfile <out_file> specify an alternative output script filename to the default which is the input xsil filename with the .xsil
       extension changed to either .m for the matlab m-file or .sci for the scilab script file

EXAMPLES

       bash$ xsil2graphics nlse.xsil

       Generates the output nlse.m to load the data into matlab

       bash$ xsil2graphics -m nlse.xsil

       Also generates the output nlse.m but explicitly sets matlab to be the output format

       bash$ xsil2graphics --scilab nlse.xsil

       Generates the output nlse.sci to load the data into scilab

       bash$ xsil2graphics --outfile nlse_new.m nlse.xsil

       Generates the output nlse_new.m to load the data into matlab

AUTHORS

       Originally written by Greg Collecutt

       Maintained by Paul Cochrane with code contributed by Joe Hope

BUGS

       No known bugs.

SEE ALSO

       xmds(1), loadxsil(1)

       http://www.xmds.org

COPYRIGHT

       Copyright (C) 2000-2004

       Code contributed by Greg Collecutt, Joseph Hope and Paul Cochrane

       This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by
       the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

       This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MER-
       CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

       You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation,
       Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

perl v5.8.2							    2004-06-21							  XSIL2GRAPHICS(1)
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