/*
 *  ======================================================================= 
 *  strings.c -- Exercise String and Character Functions
 *
 *  The program design is as follows:
 *
 *     Read a string that represents a file name prefix (e.g., "data")
 *     Read in a string that represents a file name in the form prefix.N
 *     Convert the file name to lower case
 *     Find the . before N (beginning of string in the form .123)
 *     Check that the file name actually starts with the prefix string
 *     Copy and Convert N, still a char string, to an integer
 *     Increment the integer form of N
 *     Convert the integer N back into a string
 *     Append the new incremented N to a copy of the file prefix
 *     Print the new filename
 *
 *  ======================================================================= 
 *  Copyright (C) 1998 by Mark Austin and David Mazzoni.
 *                                                                     
 *  This software is provided "as is" without express or implied warranty.
 *  Permission is granted to use this software on any computer system,
 *  and to redistribute it freely, subject to the following restrictions:
 * 
 *  1. The authors are not responsible for the consequences of use of
 *     this software, even if they arise from defects in the software.
 *  2. The origin of this software must not be misrepresented, either
 *     by explicit claim or by omission.
 *  3. Altered versions must be plainly marked as such, and must not
 *     be misrepresented as being the original software.
 *  4. This notice is to remain intact.
 * 
 *  Written by : David Mazzoni
 *  ======================================================================= 
 */

#include <stdio.h>
#include <string.h>
#include <ctype.h>   /* for tolower decl. */
#include <stdlib.h>  /* for atoi decl.    */

int main( void ) {
enum { MaxString = 20 };          /* length of strings */
char  caPrefix[ MaxString ];
char  caFilename[ MaxString ];
char* cpToSuffix;
char  caSuffix[ MaxString ];
char  caNewCopy[ MaxString ];
int iCount, iSuffix;

   /* [a] : Read a string that represents a file name  */
   /*       prefix (e.g., "data")                      */

   printf( "\n" );
   printf( "Enter the lower case prefix for the " );
   printf( "data file names (e.g., \"data\"):" );
   scanf( "%s%*c", caPrefix );

   /* [b] : Read in a string that represents a file name */
   /*       in the form prefix N.                        */

   printf( "Enter the filename (e.g., \"data.122\"):" );
   scanf( "%s%*c", caFilename );
  
   /* [c] : Convert the file name to lower case */

   for( iCount = 0; iCount < strlen(caFilename); iCount++ )
      caFilename[iCount] = tolower(caFilename[iCount] );

   /* [d] : Find the . before N (beginning of string in the form .123) */

   cpToSuffix = strchr( caFilename, '.' );

   /* [e] : 0 terminate prefix, save pointer to suffix */

   *cpToSuffix++ = 0;

   /* [f] : Check that the file name actually starts with */
   /*       the prefix string.                            */

   strcpy( caNewCopy, caFilename );
   if( strcmp( caNewCopy, caPrefix ) ! 0 ) {
      printf( "\nImproper suffix error.  Aborting.\n" );
      return 1;
   }

   /* [g] : Copy and Convert N, still a char string, to an integer */

   strcpy( caSuffix, cpToSuffix );
   iSuffix = atoi( caSuffix );

   /* [h] : Increment the integer form of N */

   iSuffix += 1;

   /* [i] : Convert the integer N back into a string */

   sprintf( caSuffix, "%i", iSuffix );

   /* [j] : Append the new incremented N to a copy of the file prefix */

   strcat( caNewCopy, "." );
   strcat( caNewCopy, caSuffix );

   /* [k] : Print the new filename */

   printf( "\nThe new filename is %s\n", caNewCopy );
   return 0;
}