text: // Copyright (C) 2011  Davis E. King (davis@dlib.net)
  // License: Boost Software License   See LICENSE.txt for the full license.
  
  #include "common.h"
  #include <fstream>
  #include <dlib/error.h>
  
  // ----------------------------------------------------------------------------------------
  
  std::string strip_path (
      const std::string& str,
      const std::string& prefix
  )
  {
      unsigned long i;
      for (i = 0; i < str.size() && i < prefix.size(); ++i)
      {
          if (str[i] != prefix[i]) 
              return str;
      }
  
      if (i < str.size() && (str[i] == '/' || str[i] == '\\'))
          ++i;
  
      return str.substr(i);
  }
  
  // ----------------------------------------------------------------------------------------
  
  void make_empty_file (
      const std::string& filename
  )
  {
      std::ofstream fout(filename.c_str());
      if (!fout)
          throw dlib::error("ERROR: Unable to open " + filename + " for writing.");
  }
  
  // ----------------------------------------------------------------------------------------
  
  std::string to_png_name (const std::string& filename)
  {
      std::string::size_type pos = filename.find_last_of(".");
      if (pos == std::string::npos)
          throw dlib::error("invalid filename: " + filename);
      return filename.substr(0,pos) + ".png";
  }
  
  // ----------------------------------------------------------------------------------------
  
  std::string to_jpg_name (const std::string& filename)
  {
      std::string::size_type pos = filename.find_last_of(".");
      if (pos == std::string::npos)
          throw dlib::error("invalid filename: " + filename);
      return filename.substr(0,pos) + ".jpg";
  }
  
  // ----------------------------------------------------------------------------------------
  
  #ifdef DLIB_WEBP_SUPPORT
  std::string to_webp_name (const std::string& filename)
  {
      std::string::size_type pos = filename.find_last_of(".");
      if (pos == std::string::npos)
          throw dlib::error("invalid filename: " + filename);
      return filename.substr(0,pos) + ".webp";
  }
  #endif
  
  // ----------------------------------------------------------------------------------------
  
  