/******  do_ifile.c

   Asks for the input file name, if necessary, and opens the file

******/

#include <stdio.h>
#include <string.h>

FILE   *do_infile(int argc, char *argv[], char *linebfr)
{
   FILE    *infile;

/**************************************************************************

    Process the INPUT file name and open the file

*/

   if ( argc > 1 )
   {
       strcpy( linebfr, argv[1]) ;
   }
   else
   {
       printf( "Enter the name of the input text file: ");
       gets(linebfr);
       if ( !strlen(linebfr) )
       {
           printf( "You must enter a file name!\n" );
           exit();
       }
   }

/* Open the header file */
   infile = fopen( linebfr, "rt" );
   if ( !infile )
   {
       printf( "Can't open input file!\n" );
       exit();
   }
   return(infile);
}