HelloWorld
: writes Hello World! to
the console
These are the main files contained in the examples. Some extra files may be needed to run the examples, and these will be found in the appropriate examples directory.
// HelloWorld.cpp
//
// Copyright (c) 2000 Symbian Ltd. All rights reserved.
#include "CommonFramework.h"
// do the example
LOCAL_C void doExampleL()
{
_LIT(KHelloWorldText,"Hello world!\n");
console->Printf(KHelloWorldText);
}
// BLD.INF
// Component description file
//
// Copyright (c) 2000 Symbian Ltd. All rights reserved.
PRJ_MMPFILES
HelloWorld.mmp
// HelloWorld.mmp
//
// Copyright (c) 2000 Symbian Ltd. All rights reserved.
// using relative paths for sourcepath and user includes
TARGET HelloWorld.exe
TARGETTYPE exe
UID 0
VENDORID 0x70000001
SOURCEPATH .
SOURCE HelloWorld.cpp
USERINCLUDE .
USERINCLUDE ..\CommonFramework
SYSTEMINCLUDE \Epoc32\include
LIBRARY euser.lib
HelloWorld
is a very simple piece of code showing how text
is written to the console. All other examples in Basics
and
System
use the same technique.
The file CommonFramework.h
contains the entry point and
all code necessary to support the example itself, including the construction of
the console and the cleanup stack. Putting code into a .h
file may
not be conventional practice, but it is useful to do so here.
The source code for this example application can be found in the directory:
examples\Basics\HelloWorld
It may be in the directory in which you installed Symbian OS, or it may
be in src\common\developerlibrary\
. It includes the two project
files needed for building: bld.inf
and the .mmp
file.
The Symbian OS build process describes how to build this application, which results in an executable called:
\epoc32\release\<target>\<urel or
udeb>\HELLOWORLD.EXE
.
Run the executable HELLOWORLD.EXE
.
Executables for the emulator targets wins
and
winscw
can be run on your PC. Executables for ARM targets must be
copied to your target platform before being run.
The example shows the use of the _LIT
macro which is used
throughout all of the examples. The macro generates a:
const static TLitC<TInt>
object and is an efficient and convenient way of generating constant literal text.
As this is a wide (Unicode) build, TLItC<TInt>
is a
typedef for TLitC16<TInt>.
#include "CommonFramework.h"
// do the example
LOCAL_C void doExampleL()
{
_LIT(KHelloWorldText,"Hello world!\n");
console->Printf(KHelloWorldText);
}
#ifndef __CommonFramework_H
#define __CommonFramework_H
#include <e32base.h>
#include <e32cons.h>
_LIT(KTxtEPOC32EX,"EXAMPLES");
_LIT(KTxtExampleCode,"Symbian OS Example Code");
_LIT(KFormatFailed,"failed: leave code=%d");
_LIT(KTxtOK,"ok");
_LIT(KTxtPressAnyKey," [press any key]");
// public
LOCAL_D CConsoleBase* console; // write all your messages to this
LOCAL_C void doExampleL(); // code this function for the real example
// private
LOCAL_C void callExampleL(); // initialize with cleanup stack, then do example
GLDEF_C TInt E32Main() // main function called by E32
{
__UHEAP_MARK;
CTrapCleanup* cleanup=CTrapCleanup::New(); // get clean-up stack
TRAPD(error,callExampleL()); // more initialization, then do example
__ASSERT_ALWAYS(!error,User::Panic(KTxtEPOC32EX,error));
delete cleanup; // destroy clean-up stack
__UHEAP_MARKEND;
return 0; // and return
}
LOCAL_C void callExampleL() // initialize and call example code under cleanup stack
{
console=Console::NewL(KTxtExampleCode,TSize(KConsFullScreen,KConsFullScreen));
CleanupStack::PushL(console);
TRAPD(error,doExampleL()); // perform example function
if (error)
console->Printf(KFormatFailed, error);
else
console->Printf(KTxtOK);
console->Printf(KTxtPressAnyKey);
console->Getch(); // get and ignore character
CleanupStack::PopAndDestroy(); // close console
}
#endif