nuttx-apps/examples/nxflat/tests/hello++/hello++3.cxx
Xiang Xiao b659f0fbdf Remove the unnecessary cast for main_t, NULL and argv
Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
2022-10-18 18:40:23 +02:00

118 lines
3.8 KiB
C++

/////////////////////////////////////////////////////////////////////////////
// apps/examples/nxflat/tests/hello++/hello++3.cxx
//
// Licensed to the Apache Software Foundation (ASF) under one or more
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. The
// ASF licenses this file to you 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.
//
/////////////////////////////////////////////////////////////////////////////
//
// This is an another trivial version of "Hello, World" design. It illustrates
//
// - Building a C++ program to use the C library and stdio
// - Basic class creation with virtual methods.
// - Static constructor and destructors (in main program only)
// - NO Streams
//
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// Included Files
/////////////////////////////////////////////////////////////////////////////
#include <cstdio>
/////////////////////////////////////////////////////////////////////////////
// Classes
/////////////////////////////////////////////////////////////////////////////
class CThingSayer
{
const char *szWhatToSay;
public:
CThingSayer(void);
virtual ~CThingSayer(void);
virtual void Initialize(const char *czSayThis);
virtual void SayThing(void);
};
// 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;
// These are implementations of the methods of the CThingSayer class
CThingSayer::CThingSayer(void)
{
printf("CThingSayer::CThingSayer: I am!\n");
szWhatToSay = NULL;
}
CThingSayer::~CThingSayer(void)
{
printf("CThingSayer::~CThingSayer: I cease to be\n");
if (szWhatToSay)
{
printf("CThingSayer::~CThingSayer: I will never say '%s' again\n",
szWhatToSay);
}
szWhatToSay = NULL;
}
void CThingSayer::Initialize(const char *czSayThis)
{
printf("CThingSayer::Initialize: When told, I will say '%s'\n",
czSayThis);
szWhatToSay = czSayThis;
}
void CThingSayer::SayThing(void)
{
printf("CThingSayer::SayThing: I am now saying '%s'\n", szWhatToSay);
}
/////////////////////////////////////////////////////////////////////////////
// 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
printf("main: Started. MyThingSayer should already exist\n");
// Tell MyThingSayer that "Hello, World!" is the string to be said
printf("main: Calling MyThingSayer.Initialize\n");
MyThingSayer.Initialize("Hello, World!");
// Tell MyThingSayer to say the thing we told it to say
printf("main: Calling MyThingSayer.SayThing\n");
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
printf("main: Returning. MyThingSayer should be destroyed\n");
return 0;
}