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Full Discussion: C Code to read a word from file
Top Forums Programming C Code to read a word from file Post 302906245 by achenle on Wednesday 18th of June 2014 09:39:38 AM
Old 06-18-2014
How does your code get the word(s) to search for? Is there only one word, or are there more than one?

That could make a big difference in how you design your code.

Also, what do you know about the file before you start processing it? The more data you have, the better you can make your program perform. Because for a large file, scalability is going to be a problem.

Assuming you get the words to be searched via command line arguments, something like this could search a single line:

Code:
int searchLine( char *line, char **argv, int argc, int *counts )
{
    /* assume no matches - that means the "counts" array can be reused */
    int rc = 0;

    int ii;
    int jj;

    /* check input values to prevent SEGV */
    if ( ( NULL == line ) || ( NULL == argv ) || ( NULL == counts ) )
    {
        /* probably should emit an error here */
        return( rc );
    }

    /* zero out the counts array */
    for ( ii = 0, ii < argc, ii++ )
    {
        counts[ ii ] = 0;
    }

    /* determine how long the line is */
    int len = strlen( line );

    /* check if we match any of the words passed in starting at each
        character in the line of text */
    for ( ii = 0; ii < len; ii++ )
    {
        /* start from 1 instead of 0, assuming argv is the commaind-line
            args passed to main(), so argv[ 0 ] is the executable file name */
        for ( jj = 1; jj < argc; jj++ )
        {
            /* on a match, increment the count for that word and set return
                code to flag a match was found */
            if ( 0 == strcmp( &( line[ ii ] ), argv[ jj ] ) )
            {
                rc = 1;
                ( counts[ jj ] )++;
            }
        }
    }

    return( rc );
}

That should work to count words in a single line of text.

One thing that's important: having a maximum line length per file. Is that specified? If so, you can use "fgets()" and read one line at a time very simply:

Code:
FILE *ff;
char *result;
char line[ MAX_LINE_LENGTH ];

ff = fopen( fileName, "r" );
if ( NULL == ff )
{
    return( ERROR );
}
do
{
    result = fgets( line, sizeof( line ) / sizeof( line[ 0 ] ), ff );
    if ( NULL != result )
    {
        /* process line of text */
    }
}
while ( NULL != result );
fclose( ff );

 

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LEARN ABOUT CENTOS

wc

WC(1)								   User Commands							     WC(1)

NAME

       wc - print newline, word, and byte counts for each file

SYNOPSIS

       wc [OPTION]... [FILE]...
       wc [OPTION]... --files0-from=F

DESCRIPTION

       Print  newline, word, and byte counts for each FILE, and a total line if more than one FILE is specified.  With no FILE, or when FILE is -,
       read standard input.  A word is a non-zero-length sequence of characters delimited by white space.  The options below may be used to select
       which counts are printed, always in the following order: newline, word, character, byte, maximum line length.

       -c, --bytes
	      print the byte counts

       -m, --chars
	      print the character counts

       -l, --lines
	      print the newline counts

       --files0-from=F
	      read input from the files specified by NUL-terminated names in file F; If F is - then read names from standard input

       -L, --max-line-length
	      print the length of the longest line

       -w, --words
	      print the word counts

       --help display this help and exit

       --version
	      output version information and exit

       GNU coreutils online help: <http://www.gnu.org/software/coreutils/> Report wc translation bugs to <http://translationproject.org/team/>

AUTHOR

       Written by Paul Rubin and David MacKenzie.

COPYRIGHT

       Copyright (C) 2013 Free Software Foundation, Inc.  License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
       This is free software: you are free to change and redistribute it.  There is NO WARRANTY, to the extent permitted by law.

SEE ALSO

       The full documentation for wc is maintained as a Texinfo manual.  If the info and wc programs are properly installed at your site, the com-
       mand

	      info coreutils 'wc invocation'

       should give you access to the complete manual.

GNU coreutils 8.22						     June 2014								     WC(1)
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