On , Leon Varghese (3:800/846@fidonet) wrote: 
 > I have a string:
 > "a:\cpp\filename.cdm" and I want to change its file extension
 > so it reads  "a:\cpp\filename.trk"
  It's been done, albeit in C rather than C++. Here it is, from SNIPPETS:
/* +++Date last modified: 02-Nov-1995 */
/*
**  chgext.c - Change a file's extension
**
**  public domain by Bob Stout
**
**  Arguments: 1 - Pathname
**             2 - Old extension (NULL if don't care)
**             3 - New extension
**
**  Returns: Pathname or NULL if failed
**
**  Note: Pathname buffer must be long enough to append new extension
**
**  Side effect: Converts Unix style pathnames to DOS style
*/
#include 
#include 
#include "filnames.h"
char *chgext(char *path, char *oldext, char *newext)
{
      char *p;
      /* Convert to DOS-style path name */
      for (p = path; *p; ++p)
            if ('/' == *p)
                  *p = '\\';
      /* Find extension or point to end for appending */
      if (NULL == (p = strrchr(path, '.')) || NULL != strchr(p, '\\'))
            p = strcpy(&path[strlen(path)], ".");
      ++p;
      /* Check for old extension */
      if (oldext && strcmp(p, oldext))
            return NULL;
      /* Add new extension */
      while ('.' == *newext)
            ++newext;
      strncpy(p, newext, 3);
      /*
      ** Added to insure string is properly terminated. Without this, if
      ** the new extension is longer than the old, we lose the terminator.
      */
      p[strlen(newext)] = '\0';
      return path;
}
#ifdef TEST
main(int argc, char *argv[])
{
      char *retval, *old_ext = NULL, path[128];
      if (2 > argc)
      {
            puts("Usage: CHGEXT path [old_ext]");
            puts("\nChanges extension to \".TST\"");
            puts("Old extension optional");
            return -1;
      }
      strcpy(path, strupr(argv[1]));
      if (2 < argc)
            old_ext = strupr(argv[2]);
      if (NULL == (retval = chgext(path, old_ext, ".TSTstuff")))
            puts("chgext() failed");
      else  printf("chgext(%s, %s, TST)\n...returned...\n%s\n", argv[1],
            old_ext ? old_ext : "NULL", path);
      return (NULL == retval);
}
#endif /* TEST */
 
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