Exception.h Example File

 // -*- mode:c++; tab-width:2; indent-tabs-mode:nil; c-basic-offset:2 -*-
 #ifndef __EXCEPTION_H__
 #define __EXCEPTION_H__

 /*
  *  Exception.h
  *  ZXing
  *
  *  Copyright 2010 ZXing authors All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include <string>
 #include <exception>

 namespace zxing {

 class Exception : public std::exception {
 private:
   char const* const message;

 public:
   Exception() throw() : message(0) {}
   Exception(const char* msg) throw() : message(copy(msg)) {}
   Exception(Exception const& that) throw() : std::exception(that), message(copy(that.message)) {}
   ~Exception() throw() {
     if(message) {
       deleteMessage();
     }
   }
   char const* what() const throw() {return message ? message : "";}

 private:
   static char const* copy(char const*);
   void deleteMessage();
 };

 }

 #endif // __EXCEPTION_H__