I have following code where the idea is to read a text file line by line and save the current position m_numBytesRead. So if I break the loop (on my case to split text parsing by chunks on big files) and I try to access a second time by making a Seek of m_numBytesRead-1, the ReadString is not geting the begin of the line as I expected.
CStdioFile fileLog;
if (fileLog.Open(m_strReadFileName, CFile::modeNoTruncate | CFile::modeRead | CFile::shareDenyNone))
{
if (m_numBytesRead > 0)
fileLog.CStdioFile::Seek(m_numBytesRead-1, CFile::begin);
bool bBreakLoop = false;
while (fileLog.ReadString(strLine) && !bBreakLoop)
{
// any condition to set bBreakLoop after few MB read...
if (!bBreakLoop)
{
m_numBytesRead = fileLog.CStdioFile::GetPosition();
}
};
fileLog.Close();
}
By debuging more in detail and comparing with the indexes I get on Notepad++, it seems that the CStdioFile::GetPosition() is not giving correct value, begining of new line to be read, but few bytes (12 on my case) more...
Is is a bug on MFC or is there something I'm missing there ? Does someone see similar issues ?
Note that I'm using VS2010 on Windows 7.
Add open mode CFile::typeBinary to get byte-exact offsets. The default mode is text, which performs newline conversion which may mess up offsets.