///////////////////////////////////////////////////////////////////////////// // examples/elf/tests/helloxx/hello++4.c // // Copyright (C) 2012 Gregory Nutt. All rights reserved. // Author: Gregory Nutt // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions // are met: // // 1. Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // 2. Redistributions in binary form must reproduce the above copyright // notice, this list of conditions and the following disclaimer in // the documentation and/or other materials provided with the // distribution. // 3. Neither the name NuttX nor the names of its contributors may be // used to endorse or promote products derived from this software // without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS // FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE // COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, // BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS // OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED // AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT // LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN // ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE // POSSIBILITY OF SUCH DAMAGE. // ///////////////////////////////////////////////////////////////////////////// // // This is an excessively complex version of "Hello, World" design to // illustrate some basic properties of C++: // // - Building a C++ program // - Streams / statically linked libstdc++ // - Static constructor and destructors (in main program only) // ///////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////// // Included Files ///////////////////////////////////////////////////////////////////////////// #include #include #ifndef NULL # define NULL ((void*)0L) #endif ///////////////////////////////////////////////////////////////////////////// // Classes ///////////////////////////////////////////////////////////////////////////// using namespace std; // A hello world sayer class class CThingSayer { const char *szWhatToSay; public: CThingSayer(void); virtual ~CThingSayer(void); virtual void Initialize(const char *czSayThis); virtual void SayThing(void); }; ///////////////////////////////////////////////////////////////////////////// // Private Data ///////////////////////////////////////////////////////////////////////////// // A static instance of the CThingSayer class. This instance MUST // be constructed by the system BEFORE the program is started at // main() and must be destructed by the system AFTER the main() // returns to the system static CThingSayer MyThingSayer; ///////////////////////////////////////////////////////////////////////////// // Method Implementations ///////////////////////////////////////////////////////////////////////////// // These are implementations of the methods of the CThingSayer class CThingSayer::CThingSayer(void) { cout << "CThingSayer::CThingSayer: I am!" << endl; szWhatToSay = (const char*)NULL; } CThingSayer::~CThingSayer(void) { cout << "CThingSayer::~CThingSayer: I cease to be" << endl; if (szWhatToSay) { cout << "CThingSayer::~CThingSayer: I will never say '" << szWhatToSay << "' again" << endl; } szWhatToSay = (const char*)NULL; } void CThingSayer::Initialize(const char *czSayThis) { cout << "CThingSayer::Initialize: When told, I will say '" << czSayThis << "'" << endl; szWhatToSay = czSayThis; } void CThingSayer::SayThing(void) { cout << "CThingSayer::SayThing: I am now saying '" << szWhatToSay << "'" << endl; } ///////////////////////////////////////////////////////////////////////////// // Public Functions ///////////////////////////////////////////////////////////////////////////// int main(int argc, char **argv) { // We should see the message from constructor, CThingSayer::CThingSayer(), // BEFORE we see the following messages. That is proof that the // C++ static initializer is working cout << "main: Started" << endl; // Tell MyThingSayer that "Hello, World!" is the string to be said cout << "main: Calling MyThingSayer.Initialize" << endl; MyThingSayer.Initialize("Hello, World!"); // Tell MyThingSayer to say the thing we told it to say cout << "main: Calling MyThingSayer.SayThing" << endl; MyThingSayer.SayThing(); // We are finished, return. We should see the message from the // destructor, CThingSayer::~CThingSayer(), AFTER we see the following // message. That is proof that the C++ static destructor logic // is working cout << "main: Returning" << endl; return 0; }