Reading & Writing a file (uRGENT)

[Devang Shah]

Hello everybody,

I have a structure of the following type,

data{
TInt A;
TInt B;
Tint C;
TBool D;
TBool E;
}


Now i want this structure to be written to a file and read back. Can anyone help me in solving this problem? lease provide some code so it will be clear.

Thanks in advance

[symbianyucca]

maybe you could have a look into streams, such as RFileReadStream & RFileWriteStream. I'm quite sure there are also example applications utilizing them.

yucca

[Devang Shah]

This is the code for writing, where iData contains the above declared structure,

RFileWriteStream Stream;
TInt Error = Stream.Replace(CEikonEnv::Static()->FsSession(),SaveSettingFile,EFileWrite);
if (KErrorNone == Error)
{
TRAP(Error,Stream.WriteL(TUint 8*)&(iData),sizeof(class ListData)));
Stream.close();
}

can u give me the code to read,...

thanks in advance
thanks for replying yucca

[symbianyucca]

see this for a short example: http://forum.newlc.com/viewtopic.php?t=5720

basically, I think you could just write the values after each other in order and then read them out in similar way.

yucca

[template60]

An alternative to streams...

class TData // in Symbian this is a T-class
{
TInt A;
TInt B;
Tint C;
TBool D;
TBool E;
}

//

void CMyClass::SaveToFileL(const TData& aData)
{
TPckg<TData> dataBuf(aData);

RFile file;
User::LeaveIfError(file.Replace(iFs, KMyFileName, EFileWrite | EFileStream));
CleanupClosePushL(file);
User::LeaveIfError(file.Write(dataBuf));
CleanupStack::PopAndDestroy(&file); // closes file
}

you could just reverse the above to read the data back in

[relliott98]

Hello,

My requirement is to read a file one line at a time. I have the following code however when I read the last line (which contains EOF) the program halts with epoc error. I cannot TRAP. Any ideas?

Thanks,
RE

TInt fSize;
TInt iReadBytes = 0;
RFile file;
RFs fsSession;
_LIT( KContactFile,"\\system\\Apps\\PSCLIENT\\contacts.txt");
User::LeaveIfError(fsSession.Connect());
TInt err = file.Open(fsSession,KContactFile, EFileRead);
if (err != KErrNotFound)
{
// read the Contact file
file.Size(fSize);
RFile f = file;
RFileReadStream stream(f);
TBuf8<128> *buf = new(ELeave)TBuf8<128>;
do {
TRAPD(err, stream.ReadL(*buf,(TChar)'\n'));
if (err == KErrEof)
{
int i = 1;
}
iReadBytes += buf->Length();
buf->Delete(0, 128);
} while (iReadBytes < fSize);
stream.Close();
fsSession.Close();
}

[kummel2]

Hi

I learned how to read and write data while programming Epoc for Psion Revo some years ago. I still use the same way and it works perfect.

Search for information on Externalize/Internalize. Read and implement once and I guarantee you will like it.


/T

[GeKI]

Hello,

How to write the following struct into a file ? can I use TPckgBuf ? and how.

struct TLicensePlugin
{
TInt iPluginId;
TInt iSubscriptionType;
TInt iDaysLeft;
};

struct TLicenseLocal
{
TInt iVersion;
TBuf<50> iLastTime;
TBuf<50> iUser;
TBuf<50> iPwd;
CArrayFixFlat<TLicensePlugin>* iPlugins;
};

If I don't include the last line, iPlugins, the structure is saved and loaded perfectly using the code posted before my post.

But I have this array of TLicensePlugin, that is another struct.

Do I need to write separately into a loop the elements of this array or can I insert somehow into the whole TPckgBuf buffer?

thanks.

[template60]

Hi

TLicenseLocal in this instance is really not a T class/struct but rather a C class/struct. This is because is contains (owns) a C class which requires proper destruction.

I suggest you implement a new class called CLicenseLocal deriving from CBase. Add to this InternalizeL() and ExternalizeL() functions as well as a destructor that properly deletes all members.

In the InternalizeL and ExternalizeL you'll need to iteratively write each plugin data to the file. You'd probably also want to write the count so that you are able to easily InternalizeL.

Hope this helps.

[anoopd]

Hi all,

How can we read an ascii file of encoding type ANSI ?????? or how can we convert TBuf8 to TBuf<256> ???????

Thanks,
Anoop

[aswathy]

Hi all,

How can we convert file of encoding type ANSI to unicode file ??????

Thanks,
Aswathy

[barberry]

could you give me some help???
I need example code about writing arbitrary binary data in the file
thank you in advance