Array of datas returning issue, Overwriting

Question

Hi, Please help me on this Here i want to save the converted data into new pointers. But everytime the data is overwriting with most recent data. Please check my code

 TCHAR nameBuffer[256]; //Globally Declared

 void Caller()
 {
 TCHAR* ptszSecondInFile= QStringToTCharBuffer(userName);
 TCHAR* ptszOutFile=QStringToTCharBuffer(Destinationfilename);
 }

TCHAR *dllmerge::QStringToTCharBuffer( QString buffer )
{
    memset(nameBuffer, 0, sizeof(nameBuffer));
#if UNICODE
_tcscpy_s(nameBuffer, _countof(nameBuffer), buffer.toUtf8());
#else
_tcscpy_s(nameBuffer, _countof(nameBuffer), buffer.toLocal8Bit());
#endif
_tprintf( _T( "nameBuffer %s\n" ), nameBuffer );
return nameBuffer;
 }

I am gettting ptszSecondInFile and ptszOutFile both same answer. Is it possible to do with TCHAR* nameBuffer[256];

Answer 1

Seems you use the global variable nameBuffer in the QStringToTCharBuffer. Make it local... Or just copy the value of nameBuffer in the Caller between the two calls... otherwise the second call will overwrite the value of the global variable...

As a programming advice for the future: DO NOT USE GLOBAL VARIABLES UNLESS YOU REALLY HAVE TO!!! In this case you don't have to use it.

Answer 2

You need memory to hold each string that you need at once so a global buffer isn't going to work here. Either have your QStringToTCharBuffer function allocate a new char buffer for each string or pass a char buffer to the function. I'd advise the second one as you're more likely to forget that a function allocates memory.

i.e:

TCHAR *dllmerge::QStringToTCharBuffer( QString buffer )
{
    TCHAR* nameBuffer = new TCHAR[256];

    memset(nameBuffer, 0, sizeof(nameBuffer));
#if UNICODE
    _tcscpy_s(nameBuffer, _countof(nameBuffer), buffer.toUtf8());
#else
    _tcscpy_s(nameBuffer, _countof(nameBuffer), buffer.toLocal8Bit());
#endif
    _tprintf( _T( "nameBuffer %s\n" ), nameBuffer );
    return nameBuffer;
}

vs:

void Caller()
{
    const int maxSize = 256;
    TCHAR szSecondInFile[maxSize];
    TCHAR szOutFile[maxSize];
    QStringToTCharBuffer( userName, szSecondInFile, maxSize );
    QStringToTCharBuffer( Destinationfilename, szOutFile, maxSize );
}

dllmerge::QStringToTCharBuffer( QString buffer, TCHAR* pOutString, const int size )

etc.