/*          Tolower           */


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

#define MAXFILENAMELEN 40
#define MAXLEN 60
#define NULL_ 0

void convert( char *file_name );
char *strlwr( char *Word );

void main( int argc, char **argv )
{
   char filename [MAXFILENAMELEN];

     if( argc != 2 )
        {
        printf( "\n\nFilename to convert to lower case? " );
        gets( filename );
        }
     else
        strcpy( filename, *( argv + 1 ) );

     convert( filename ); 
}

void convert( char *fname )
{
   char word [MAXLEN];
     
   FILE *fps;

      fps = fopen( fname, "r" );

      while( !feof( fps ) )
         {
         fgets( word, MAXLEN - 1, fps );

         if( feof( fps ) ) break;

         strlwr( word ); 
         printf( word );

         }

      fclose( fps );

     
      return;
}

char *strlwr ( char *wd )
{

   char *wptr;

      wptr = wd;

      while( *wptr )
         {
         *wptr = tolower( *wptr );
         wptr++;
         }

         *wptr = NULL_;

      return( wptr );
}