Function parameter const TdesC& aAMRFilename fill with data?

[FrankTheFox]

Hi,

my problem is illustrated by the following code...

void CServerSettings::CreateAMRFileNameL(const TDesC aFilePath, const TDesC& aAMRFilename )
	{
	
	TInt64 currentTimeMillis = (static_cast<CTMSAppUi*>( iEikonEnv->EikAppUi() ) )->iDatabaseEngine->GetCurrentTimeMillis();
	
	TBuf<255> caption( NULL );
	TBuf<255> caption2( NULL );
	HBufC* buffer = HBufC::NewLC( 255 );
	HBufC* result = HBufC::NewLC( 255 );

	_LIT( KFormat, "%Ld" );
	_LIT( KFileExtension, ".amr" );		


	caption.Append( aFilePath );
	caption.Append( KFormat );
        caption.Append( KFileExtension );
	
	
	caption2.Format( caption, currentTimeMillis );
	buffer->Des().Append( aFilePath );
	buffer->Des().Append( KFormat() );
        buffer->Des().Append( KFileExtension() );
	
	result->Des().Format( *buffer, currentTimeMillis );
	
	
	CleanupStack::PopAndDestroy( buffer );
	
	aAMRFilename = &caption2;
	
	CleanupStack::PopAndDestroy( result );
	}

I want to put a filepath like "C:\\Data\\" to my method
inside my method i want to append "%Ld" (my format) then format my buffer with filename + extension.
And then put the result back to aAMRFilename. How do i do this?


Greetz
Franky


(These TDesC, HBufC*, TPtr stuff drives me mad)

[anttijuu]

const TDesC & means that the parameter is a constant parameter and the descriptor is constant too. If you really want to modify the parameter, do either:

void CServerSettings::CreateAMRFileNameL(const TDesC & aFilePath, TDesC & aAMRFilename )
	{
...
	TPtr ptr(aAMRFilename.Des());
        ptr = KMyConstantDescriptor;
        ptr.Append(KMoreText);
        ptr.Format(....);

So now the descriptor is constant, the parameter not. But you can now modify the value using Des().

Or, even easier, use the abstract modifiable descriptor type:

void CServerSettings::CreateAMRFileNameL(const TDesC & aFilePath, TDes & aAMRFilename )
	{
...
        aAMRFilename = KMyConstantDescriptor;
        aAMRFilename.Append(KMoreText);
        aAMRFilename.Format(....);

Note also that your code missed the "&" in the aFilePath parameter.

[FrankTheFox]

Hey,


thanks, yes this is right. Now i am able to get this done. Thanks a lot!


Greetz
Franky

[hotcheese]

No disrespect but maybe you should read a C++ book, you've been coming on the board for a while now, and const is a fundamental keyword in both C and C++ whose meaning is independant of Symbian C++.


ANd you should review this, there is a bug in the header definition, as has been pointed out:
void CServerSettings::CreateAMRFileNameL(const TDesC aFilePath, const TDesC& aAMRFilename )


And this is not correct:

void CServerSettings::CreateAMRFileNameL(const TDesC & aFilePath, TDesC & aAMRFilename )



Constant descriptors should be:
const TDesC&

non constant descriptors should be:
TDes&


As shown in the last example, the first should not be applied.

Not const TDes&
Not TDesC&
etc.