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Chameleon: a C++ class that can act as a number and a string

The chamaeleon is a strange animal. Once it looks green, then it looks blue. Very strange indeed! Very much so with this class. It might look like a string, then again, it might look like a double.

The Header File

Chameleon.h
/* 
   Chameleon.h

   Copyright (C) 2002-2004 René Nyffenegger

   This source code is provided 'as-is', without any express or implied
   warranty. In no event will the author be held liable for any damages
   arising from the use of this software.

   Permission is granted to anyone to use this software for any purpose,
   including commercial applications, and to alter it and redistribute it
   freely, subject to the following restrictions:

   1. The origin of this source code must not be misrepresented; you must not
      claim that you wrote the original source code. If you use this source code
      in a product, an acknowledgment in the product documentation would be
      appreciated but is not required.

   2. Altered source versions must be plainly marked as such, and must not be
      misrepresented as being the original source code.

   3. This notice may not be removed or altered from any source distribution.

   René Nyffenegger rene.nyffenegger@adp-gmbh.ch
*/

#ifndef CHAMELEON_H__
#define CHAMELEON_H__

#include <string>

class Chameleon {
public:
  Chameleon() {};
  explicit Chameleon(const std::string&);
  explicit Chameleon(double);
  explicit Chameleon(const char*);

  Chameleon(const Chameleon&);
  Chameleon& operator=(Chameleon const&);

  Chameleon& operator=(double);
  Chameleon& operator=(std::string const&);

public:
  operator std::string() const;
  operator double     () const;
private:
  std::string value_;
};

#endif

The Implementation File

Chameleon.cpp
/* 
   Chameleon.cpp

   Copyright (C) 2002-2004 René Nyffenegger

   This source code is provided 'as-is', without any express or implied
   warranty. In no event will the author be held liable for any damages
   arising from the use of this software.

   Permission is granted to anyone to use this software for any purpose,
   including commercial applications, and to alter it and redistribute it
   freely, subject to the following restrictions:

   1. The origin of this source code must not be misrepresented; you must not
      claim that you wrote the original source code. If you use this source code
      in a product, an acknowledgment in the product documentation would be
      appreciated but is not required.

   2. Altered source versions must be plainly marked as such, and must not be
      misrepresented as being the original source code.

   3. This notice may not be removed or altered from any source distribution.

   René Nyffenegger rene.nyffenegger@adp-gmbh.ch
*/

#include <string>
#include <sstream>

#include "Chameleon.h"

Chameleon::Chameleon(std::string const& value) {
  value_=value;
}

#include <iostream>

Chameleon::Chameleon(const char* c) {
  value_=c;
}

Chameleon::Chameleon(double d) {
  std::stringstream s;
  s<<d;
  value_=s.str();
}

Chameleon::Chameleon(Chameleon const& other) {
  value_=other.value_;
}

Chameleon& Chameleon::operator=(Chameleon const& other) {
  value_=other.value_;
  return *this;
}

Chameleon& Chameleon::operator=(double i) {
  std::stringstream s;
  s << i;
  value_ = s.str();
  return *this;
}

Chameleon& Chameleon::operator=(std::string const& s) {
  value_=s;
  return *this;
}

Chameleon::operator std::string() const {
  return value_;
}

Chameleon::operator double() const {
  return atof(value_.c_str());
}
This class is used in the class ConfigFile which can be used to read numerical and textual data from a config file.