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Full Discussion: trouble understanding file option and command line arguments
Homework and Emergencies Homework & Coursework Questions trouble understanding file option and command line arguments Post 302558629 by heywoodfloyd on Saturday 24th of September 2011 03:01:08 PM
Old 09-24-2011
trouble understanding file option and command line arguments
Hi,

I am creating a program with the C language that simulates the WC command in Unix. My program needs to count lines, bytes and words. I have not added the code to count bytes and words yet. I am having trouble understanding what the file option/flag '-' does. I can not visualize how it moves through program code. argc and argv look at one line at a time and they only look at what is on the command line. I am not sure how a program is broken up into files for WC to read.

this is the code I have so far:

Code:
/* wc simulate */

#include <stdio.h>
#include <stdlib.h>

char *pgmname; /* name of this program */

int line_count = 0;
int word_count = 0;
int byte_count = 0;

FILE *fp;

void main(argc, argv)

int argc; char *argv[];
{


int i; 
char *cp;

pgmname = argv[0];
fp = stdin;

for(i = 1; i < argc; i++) {
        cp = argv[i];
        if(*cp == '-'){
                if(*++cp == '\n'){
                        line_count++;}
                
                
        }

        else {
                  if(fp != stdin) {
                   fprintf(stderr, "%s: too many arguments\n", pgmname);
                   exit(1);
                }

                fp = fopen(cp, "r")
                if(fp == NULL) {             
                   fprintf(stderr, "%s: unable to read %s\n", pgmname, cp);
                   exit(1);
                }

        }

                printf("%d\n", line_count);
}

                

}

Right now I have code to just count the lines. I am testing the program on a hello world program below:

Code:
#include <stdio.h>

main()
{
printf("Hello World!\n");
}

when I test the program, I get 0 for line count.

California State University, Northridge, USA, Prof Gabrovsky, Comp 322
 

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LEARN ABOUT DEBIAN

pospell

pospell(1)							   User Manuals 							pospell(1)

NAME

       pospell - Run a program on the translation strings of a .po-file

SYNOPSIS

       pospell [-l language ] [-fsv] -n pofile -p program [-- [ arguments...  ]]

DESCRIPTION

       pospell copies the translations from the pofile to a temporary file (called the spellfile) and then calls program with its arguments.  pro-
       gram is supposed to somehow change the spellfile.  It is typically a spell checker. Afterwards the possibly changed translations in  spell-
       file is copied back into the pofile.

       If pofile is specified as - then pospell will act as a filter, i.e. standard input and standard output will be used.

       %f in the arguments will be expanded to the name of the spellfile, or - if the -f option is used. Use %% for a real % character.

       All  comment  lines in the pofile are replaced with lines with "#" as the only character in the spellfile.  The msgid strings with original
       text in the pofile are replaced with lines with ">" and "]" as the only characters in the spellfile.  The msgstr strings with file  headers
       (i.e. strings without corresponding msgid strings) are replaced with lines with ")" and "]" as the only characters in the spellfile.  Don't
       change or remove these lines from the spellfile - they are used when the spellfile and the pofile are merged  together  after  running  the
       program.

       The  normal  msgstr  strings  are  copied  to  the spellfile with some changes: 1) The word msgstr and everything else before the string is
       replaced by a "+" character.  2) Strings with C escape sequences followed by a letter like "one	two"  are  split  to  parts  like  "one	"
       "two".  3) Leading whitespace in continuation lines is removed.	The changes of kind 1) and 2) are undone when the spellfile is copied back
       into the pofile, but removed whitespace will not be restored.

OPTIONS

       -f     The called program is a filter so don't make a temporary file, but pipe the spellfile to its standard input and read  it	back  from
	      its standard output.

       -l language
	      Only translations with the indicated language code are copied to the spellfile.

       -s     Quit with an error message if unrecognized items are found in the pofile or spellfile.

       -v     Print the version and exit.

FILES

       pospell uses one or two temporary files with names given by the mkstemp(3) or the tmpnam(3) function.

BUGS

       If some system call gives an unexpected error pospell will stop immediately with an error message leaving its temporary files.

AUTHOR

       Byrial Jensen <byrial@image.dk>

SEE ALSO

       The GNU gettext utilities.

       newsbody(1).

Unix								    APRIL 2000								pospell(1)
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