rev.c

At can be given its arguments in a file. You can comment out lines by preceding them with either #

/*
* REV.C - Reverse lines of a file.
*
* PROGRAMMER:	    Martti Ylikoski
* CREATED:	    11.12.1990
*/
static char* VERSION= "Version 1.1. Copyright (c) Martti Ylikoski, 1990,1991. " ;
/*
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <param.h>
#include <paramstd.h>

static char *progname ;

extern unsigned long pflags ;

ParamEntry pentry[12] = {
     "P", &ParamSetPause, 0,
     "F", &ParamSetFold, 0,
     "V", &ParamSetVerbose, 0,
     "R", &ParamSetReport, 0,
     "S", &ParamSetSubDirs, 0,
     "?", &ParamSetHelp, 1,
     "H", &ParamSetHelp, 1,
     "NOD", &ParamSetNoDefault, 0,
     "TEST", &ParamSetTest, 0,
     "Y", &ParamSetYes, 0,
     "N", &ParamSetTest, 0,
     "\0", NULL, 0
} ;

ParamBlock params = {
    "/-",   IGNORECASE | NOPRIORITY | NOTRIGGERSALLOWED ,
    pentry
} ;

int main(int argc, char *argv[])
{
FILE *fptr ;
int i ;

   progname = argv[0] ;

   ParamHandle(&params, &argc, argv) ;

   if (pflags & PA_HELP)
   {
      printf("%s - reverse lines of a file.\n", progname) ;
      puts(VERSION) ;
      puts("Usage: rev [file(s)] [- | /H | /?]") ;
      return( 0 ) ;
   }

   if (argc == 1)
      rev("-") ;
   else
   {
      for (i = 1 ; i < argc ; i++)
	 if (argv[i] != NULL)
	   rev(argv[i]) ;
   }
   return( 0 ) ;
}

int rev (char *fname)
{
FILE *fptr ;
int i ;
char buf[512] ;

   /* open file */
   if (strcmp(fname, "-") == 0)
      fptr = stdin ;
   else
      if ((fptr = fopen(fname, "r")) == NULL)
      {
	 printf("%s: unable to open file %s for reading...\n", progname, fname) ;
	 printf("Exiting...\n") ;
	 return( 1 ) ;
      }

   while (feof(fptr) == 0 && ferror(fptr) == 0)
   {
      fgets(buf, sizeof(buf) - 1, fptr) ;

      if (feof(fptr) != 0 || ferror (fptr) != 0)
	 break ;

      buf[sizeof(buf) - 1] = '\0' ;
      strrev(buf) ;
      fputs(buf, stdout) ;
   }

   /* close file */
   fclose ( fptr ) ;
}