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examples/Base/BufsAndStrings/rbufexample/rbufexample.cpp

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// Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies).
// All rights reserved.
// This component and the accompanying materials are made available
// under the terms of "Eclipse Public License v1.0"
// which accompanies this distribution, and is available
// at the URL "http://www.eclipse.org/legal/epl-v10.html".
//
// Initial Contributors:
// Nokia Corporation - initial contribution.
//
// Contributors:
//
// Description:
// This example program demonstrates how to use the resizable buffer descriptor class RBuf.
//



#include "rbufexample.h"

const TInt KLargeBufSize = 15;
const TInt KSmallBufSize = 3;
const TInt KMedBufSize = 7;

_LIT(KFailed, "\n Error occurred");
_LIT(KPressAKey, "\n\n Press any key to continue the example\n");
_LIT(KLength,"\n  Length= %d");
_LIT(KMaxLength,"\n  MaxLength= %d");
_LIT(KBuffer1,"11111");
_LIT(KBuffer2,"22222");

CRBufExample::CRBufExample()
        {
        }

void CRBufExample::ConstructL()
        {
        _LIT(KTitle," RBuf Example");
        iConsole = Console::NewL(KTitle, TSize(KConsFullScreen, KConsFullScreen));
        
        _LIT(KWelcome," Welcome to the RBuf example application");
        iConsole->Printf(KWelcome);
        
        _LIT(KPressAKeyMsg, "\n\n Press any key to step through the example\n");
        iConsole->Printf(KPressAKeyMsg );
        iConsole->Getch();
        }

CRBufExample::~CRBufExample()
        {
        delete iConsole;
        }

CRBufExample* CRBufExample::NewL()
        {
        CRBufExample* self=new(ELeave)CRBufExample();
        CleanupStack::PushL(self);
        self->ConstructL();
        CleanupStack::Pop(self);
        return self;
        }
    
void CRBufExample::CreateRBufL()
        {
        _LIT(KCreate,"\n Creating an RBuf: \n");

        iConsole->Printf(KCreate);
        
        RBuf buf;
        
        // Create an empty buffer descriptor
        // The length is zero, the maxlength is 3
        User::LeaveIfError(buf.Create(KSmallBufSize));
        CleanupClosePushL(buf);
        
        // Get the length of the buffer
        TInt length= buf.Length();
        
        // Get the maximum length of the buffer
        TInt maxLength= buf.MaxLength();
        
        // Check that length and maximum length are not equal because it was created using Create()
        if(length != maxLength)
                {
                _LIT(KUsingCreate, "\n Using Create() API: ");
                iConsole->Printf(KUsingCreate);
                iConsole->Printf(KLength, length);
                iConsole->Printf(KMaxLength, maxLength);
                }
        else
                {
                iConsole->Printf(KFailed);
                }       

        // Deallocate the memory assigned to the buffer
        CleanupStack::PopAndDestroy(&buf);
        
        // Create buffer descriptor
        // The length is 3, the maxlength is 3
        User::LeaveIfError(buf.CreateMax(KSmallBufSize));
        CleanupClosePushL(buf);
        
        // Get the length of the buffer.
        length= buf.Length();
        
        // Get the maximum length of the buffer.
        maxLength=buf.MaxLength();
        
        // Check that length and maximum length are equal because it was created using CreateMax().
        if(length == maxLength)
                {
                _LIT(KCreateInAdvance, "\n Using CreateMax() API: ");
                iConsole->Printf(KCreateInAdvance);     
                iConsole->Printf(KLength, length);
                iConsole->Printf(KMaxLength, maxLength);
                }
        else
                {
                iConsole->Printf(KFailed);
                }       
        
        // Deallocate the memory assigned to the buffer.
        CleanupStack::PopAndDestroy(&buf);
        } 
        
void CRBufExample::CreateRBufFromExistingDesL()
        {
        RBuf buf;
        
        // Create a buffer descriptor, initialised with some text
        buf.CreateL(KBuffer1);
        
        _LIT(KCreateFromExistingDes, "\n From an existing descriptor ");
        iConsole->Printf(KCreateFromExistingDes);

        // Deallocates the memory assigned to the buffer
        buf.Close();
        } 
        
void CRBufExample::CreateRBufFromHBufCL()
        {
        // Create a pointer to a heap descriptor
        HBufC* hptr = HBufC::NewL(KBuffer1().Length());
        
        // Assign some data to the heap descriptor.
        *hptr = KBuffer1; 
        
        RBuf buf;
        
        // Assign the HBufC to the buffer. This transfers ownership of the heap descriptor.
        buf.Assign(hptr);
        
        _LIT(KCreateFromHBufC, "\n From HBufC ");
        iConsole->Printf(KCreateFromHBufC);
        
        // Deallocate the memory assigned to the buffer. 
        // There is no need to free the HBufC because Assign() transferred ownership.
        buf.Close(); 
        }
        
void CRBufExample::CreateRBufFromAnotherRBufL()
        {
        RBuf buf;
        
        // Create a buffer descriptor, initialised with some text
        User::LeaveIfError(buf.Create(KBuffer1));
                
        RBuf targetBuf;
        
        // Assign one buffer to the other. 
        // Transfers ownership of the source buffer's memory to the target buffer.
        // Note that targetBuf should have no memory allocated to it beforehand
        // otherwise a memory leak will occur.
        targetBuf.Assign(buf);
        
        _LIT(KCreateFromAnotherRBuf, "\n From another RBuf");
        iConsole->Printf(KCreateFromAnotherRBuf);

        // Deallocate the memory assigned to the buffer.
        targetBuf.Close();
        }
                
void CRBufExample::CreateRBufUsingRReadStreamL()
        {
        // A handle to a file server session. 
        // This is used to create and write to/read from a file.
        RFs fs;
        
        // Connect to the file server.
        User::LeaveIfError(fs.Connect());
        CleanupClosePushL(fs);
        // Create the session path at the process's private path on the system drive.
        User::LeaveIfError(fs.CreatePrivatePath(RFs::GetSystemDrive()));

        // Set the session path to point to the process's private path on the system drive.
        User::LeaveIfError(fs.SetSessionToPrivate(RFs::GetSystemDrive()));
        
        // Declare a file stream to write to.
        RFileWriteStream wStream;
        
        _LIT(KFileName,"stream.dat");
        
        // Create a file, associates it with the stream, and prepares the stream for writing.
        User::LeaveIfError(wStream.Replace(fs, KFileName, EFileWrite));
        CleanupClosePushL(wStream);
        
        _LIT(KText, "RBuf Example");

        // Write some text to the stream.
        wStream << KText();
        wStream.CommitL();
        CleanupStack::PopAndDestroy(&wStream);
        
        // Declare a file stream to read from.
        RFileReadStream rStream;
        
        // Open the file
        User::LeaveIfError(rStream.Open(fs, KFileName, EFileRead));
        CleanupClosePushL(rStream);
        
        RBuf buf;
        CleanupClosePushL(buf);
        
        // Create the buffer by passing the open stream object to CreateL().
        buf.CreateL(rStream, KLargeBufSize);
        
        _LIT(KCreateUsingRReadStream, "\n Using RReadStream ");
        iConsole->Printf(KCreateUsingRReadStream);
        
        // Deallocate the memory assigned to the buffer, close the stream and close the file server connection
        CleanupStack::PopAndDestroy(&buf);
        CleanupStack::PopAndDestroy(&rStream);
        CleanupStack::PopAndDestroy(&fs);
        }

void CRBufExample::CreateRBufFromAllocatedMemoryL()
        {
        RBuf buf;
        
        // Allocate some memory.
        TUint16* allocatedMemory = static_cast<TUint16*>( User::Alloc( KLargeBufSize * sizeof( TUint16) ) ) ;

        // Transfer ownership of the memory to the descriptor.
        buf.Assign(allocatedMemory, KLargeBufSize);
        
        _LIT(KCreateFromAllocatedMemory, "\n By transferring ownership of allocated memory");
        iConsole->Printf(KCreateFromAllocatedMemory);
        
        iConsole->Printf(KPressAKey);
        iConsole->Getch();
        
        // Deallocate the memory assigned to the buffer.
        // There is no need to free memory here because Assign() transferred ownership.
        buf.Close(); 
        }

void CRBufExample::SwapTwoRBufsL()
        {
        _LIT(KSwapAndCopy,"\n Swapping and copying data: ");
        iConsole->Printf(KSwapAndCopy);
        
        RBuf buf1;
        
        // Create a buffer descriptor, initialised with some text
        User::LeaveIfError(buf1.Create(KBuffer1));
        CleanupClosePushL(buf1);
        
        RBuf buf2;
        
        // Create a second buffer descriptor, initialised with some text
        User::LeaveIfError(buf2.Create(KBuffer2));
        CleanupClosePushL(buf2);
        
        _LIT(KBeforeSwapping, "\n Before swapping: ");
        iConsole->Printf(KBeforeSwapping);
        
        // Print out the contents of the 2 descriptors
        _LIT(KPrintFirstdata,"\n  Data present in first descriptor is: ");
        iConsole->Printf(KPrintFirstdata);      
        iConsole->Printf(buf1);
        
        _LIT(KPrintSecondData,"\n  Data present in second descriptor is: ");
        iConsole->Printf(KPrintSecondData);     
        iConsole->Printf(buf2);
        
        // Swap them and print out the new contents
        buf1.Swap(buf2);
        
        _LIT(KAfterSwapping, "\n After swapping: ");
        iConsole->Printf(KAfterSwapping);
        
        iConsole->Printf(KPrintFirstdata);      
        iConsole->Printf(buf1);
        
        iConsole->Printf(KPrintSecondData);     
        iConsole->Printf(buf2);
        
        _LIT(KSwap, "\n Swapping between two RBufs is successful");
        iConsole->Printf(KSwap);
                        
        // Deallocate memory assigned to the 2 buffer descriptors.
        CleanupStack::PopAndDestroy(2); // buf1, buf2
        }
        
void CRBufExample::CopyDataUsingAssignmentOperatorL()
        {
        RBuf buf1;
        
        // Create a buffer descriptor, initialised with some text
        buf1.Create(KBuffer1);
        CleanupClosePushL(buf1);

        RBuf buf2;
        
        // Create a second buffer descriptor, initialised with some text
        User::LeaveIfError(buf2.Create(KBuffer2));
        CleanupClosePushL(buf2);

        // Copy data using assignment operator from one to the other. 
        // Target buffer must be long enough, otherwise a panic occurs.
        buf2= buf1;
        
        // Check the value of the buffers .
        if (buf1==buf2)
                {
                _LIT(KCopyDataUsingAssignmentOperator,"\n Copying data using assignment operator from descriptor, and RBuf is successful");
                iConsole->Printf(KCopyDataUsingAssignmentOperator);
                }
        else
                {
                iConsole->Printf(KFailed);      
                }       
        
        iConsole->Printf(KPressAKey);
    iConsole->Getch();
        
        // Deallocate memory assigned to the 2 buffer descriptors.
        CleanupStack::PopAndDestroy(2); // buf1, buf2
        }
        
void CRBufExample::ReallocateAndFreeTheMemoryBufferL()
        {
        _LIT(KReAllocAndFree,"\n Realloc and free:");
        iConsole->Printf(KReAllocAndFree);
        
        RBuf buf;
        
        // Create empty buffer descriptor with max length of KSmallBufSize.
        User::LeaveIfError(buf.Create(KSmallBufSize));
        
        // Get the length of the buffer.
        TInt length= buf.Length();
        
        // Get the maximum length of the buffer.
        TInt maxLength= buf.MaxLength();
        
        _LIT(KBeforeReAlloc,"\n Before ReAlloc: ");
        iConsole->Printf(KBeforeReAlloc);
        
        // Print out the length and max length
        iConsole->Printf(KLength, length);
        iConsole->Printf(KMaxLength, maxLength);        

        // Re-allocate the buffer descriptor. Length doesnt change but maxlength does.
        User::LeaveIfError(buf.ReAlloc(KMedBufSize));
        
        // Get the length of the buffer.
        length= buf.Length();
        
        // Get the maximum length of the reallocated buffer.
        maxLength= buf.MaxLength();
        
        _LIT(KAfterReAlloc,"\n After ReAlloc: ");
        iConsole->Printf(KAfterReAlloc);

        // Print out the length and new max length
        iConsole->Printf(KLength, length);
        iConsole->Printf(KMaxLength, maxLength);        
        
        // Free the memory buffer. It sets the length and maxlength to zero.
        User::LeaveIfError(buf.ReAlloc(0));
        
        // Get the length of the buffer.
        length= buf.Length();
        
        // Get the maximum length of the buffer.
        maxLength= buf.MaxLength();
        
        _LIT(KFreeBuffer,"\n After free: ");
        iConsole->Printf(KFreeBuffer);
        
        iConsole->Printf(KLength, length);
        iConsole->Printf(KMaxLength, maxLength);
        }
        
void CRBufExample::ReplaceAndModifyTheDataL()
        {
        RBuf buf;
        
        // Create a buffer descriptor, initialised with some text
        User::LeaveIfError(buf.Create(KBuffer1)); 
        CleanupClosePushL(buf);
                        
        _LIT(KReplaceAndModify,"\n Replace and modify: ");
        iConsole->Printf(KReplaceAndModify);
        
        // Print the original data present in the buffer.
        _LIT(KOriginalData,"\n Data present in RBuf is: ");
        iConsole->Printf(KOriginalData);
        iConsole->Printf(buf);
        
        TInt pos= 1;
        
        _LIT(KReplacedMessage,"22");
        
        TInt length= KReplacedMessage().Length();

        // Replace a portion of the data in the buffer descriptor.
        buf.Replace(pos,length, KReplacedMessage);
        
        // Print the buffer's new contents.
        _LIT(KReplacedData,"\n After replacement, data held in RBuf is: ");
        iConsole->Printf(KReplacedData);
        iConsole->Printf(buf);
        
        pos=3;
        length=1;
        
        // Delete the replacement text.
    buf.Delete(pos,length);
    
    // Print the buffer's contents again.
    _LIT(KModifiedData,"\n After modification, data held in RBuf is: ");
    iConsole->Printf(KModifiedData);
    iConsole->Printf(buf);
    
    _LIT(KReplaceAndModifyData,"\n Replacing and modifying the data held in RBuf is successful");
    iConsole->Printf(KReplaceAndModifyData);
    
    // Deallocate the memory assigned to the buffer. 
        CleanupStack::PopAndDestroy(&buf);
        }
        
void CRBufExample::CleanUpRulesL()
        {
        RBuf buf;
        
        // Create a buffer descriptor, initialised with some text
        User::LeaveIfError(buf.Create(KBuffer1));
        
        // To avoid memory leaks use RBuf::CleanupClosePushL() to push a cleanup item for the RBuf onto the cleanup stack.
        // The effect is to cause Close() to be called on the buffer descriptor if a leave occurs, 
        // or when CleanupStack::PopAndDestroy() is called.
        buf.CleanupClosePushL();
        
        // Causes Close() to be called to deallocate the memory assigned to the buffer.
        CleanupStack::PopAndDestroy(&buf);
        
        _LIT(KCleanUp,"\n RBuf cleanup is successful");
        iConsole->Printf(KCleanUp);
        
        _LIT(KExitMsg, "\n\n Press any key to exit the example");
    iConsole->Printf(KExitMsg);
        iConsole->Getch();
        }       

void MainL()
        {
        CRBufExample* app= CRBufExample::NewL();
        CleanupStack::PushL(app);
        
        // Creates empty RBuf.
        app->CreateRBufL();
        
        // Creates RBuf from an existing descriptor.
        app->CreateRBufFromExistingDesL(); 
        
        // Creates RBuf from an HBufC.
        app->CreateRBufFromHBufCL();
        
        // Creates RBuf from another RBuf.
        app->CreateRBufFromAnotherRBufL();
        
        // Create RBuf using RReadStream
        app->CreateRBufUsingRReadStreamL();
        
        // Creates RBuf from allocated memory.
        app->CreateRBufFromAllocatedMemoryL();
                
        // Swaps two RBufs.
        app->SwapTwoRBufsL();
        
        // Copies data using assignment operator.
        app->CopyDataUsingAssignmentOperatorL();
        
        // Reallocates and frees the memory buffer.
        app->ReallocateAndFreeTheMemoryBufferL();
        
        // Replaces and modifies the data in the descriptor.
        app->ReplaceAndModifyTheDataL();
        
        // Demonstrates cleanup.
        app->CleanUpRulesL();
        
        CleanupStack::PopAndDestroy(app);
        } 

GLDEF_C TInt E32Main()
        {
        __UHEAP_MARK;

        CTrapCleanup* cleanup = CTrapCleanup::New();
        if(cleanup == NULL)
                {
                return KErrNoMemory;
                }
        TRAPD(err, MainL());
        delete cleanup;

        if(err !=KErrNone)
                {
                User::Panic(KFailed, err);
                }       
                
        __UHEAP_MARKEND;
        return KErrNone;
        }
  
  
  
  
 
 
 

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Copyright ©2010 Nokia Corporation and/or its subsidiary(-ies).
All rights reserved. Unless otherwise stated, these materials are provided under the terms of the Eclipse Public License v1.0.