CFile read data to buffer

I'm trying to get all the bytes from a file to read on a BYTE* variable. I'm trying to read a whole xml file data into memory which looks like:

<?xml version="1.0" encoding="utf-8"?>
<DataBlock xmlns:xsi="" xmlns:xsd=""> <Device>3867242</Device> <Manufacturer>COMPANY LTD</Manufacturer> <Data>15</Data> <VendorID>00-291-647</VendorID> <TimeStamp>2014-08-13 12:40:11</TimeStamp>
</DataBlock>

But ending up with reading something like:

"<?xml version="1.0" encoding="utf-8"?>
<DataBlock xmlns:xsi="" xmlns:xsd=""> <Device>3867242</Device> <Manufacturer>COMPANY LTD</Manufacturer> <Data>15</Data> <VendorID>00-291-647</VendorID> <TimeStamp>2014-08-13 12:40:11</TimeStamp>
</DataBlock>ýýýý««««««««þ"

Below is the code to read it..

CFile oFile;
if(oFile.Open(filePath, CFile::modeRead) == FALSE) return NULL;
long iFileSiz = oFile.GetLength();
BYTE* pData = new BYTE[iFileSiz];
oFile.Read(pData, iFileSiz);
oFile.Close();

I'm getting some garbage character at the end of buffer or some files couldn't be read completely.

Output is captured from Visual studio debugger.

3 Answers

I don't see any problems with your code. However, I would use CByteArray instead of raw BYTE*. The following example can be used if you need to read data from binary files:

CFile oFile;
if(!oFile.Open(filePath, CFile::modeRead)) return;
CByteArray fileData;
fileData.SetSize(oFile.GetLength());
UINT bytesRead = oFile.Read(fileData.GetData(), fileData.GetSize());
oFile.Close();

If you work with text files (need to NULL terminate the data read):

ULONGLONG dwLength = oFile.GetLength();
if (dwLength == 0) return FALSE;
int nSize = (int)dwLength + 1;
CStringA sData;
try
{ LPSTR pBuffer = sData.GetBuffer(nSize); oFile.Read(pBuffer, nSize); pBuffer[(int)dwLength] = NULL; sData.ReleaseBuffer();
}
catch(CFileException* pFileException)
{ pFileException->Delete(); return;
}
catch(CMemoryException* pMemoryException)
{ pMemoryException->Delete(); return;
}
catch(...)
{ return;
}

IMPORTANT: This approach is good enough for small files. Please note that it is better to read and process huge files chunk by chunk to prevent memory allocation issues.

Post is old but I wouls like to add an answer to it, so that it will be helpful for other users in future.

CFile oFile;
if(oFile.Open(filePath, CFile::modeRead) == FALSE) return NULL;
long iFileSiz = oFile.GetLength(); // Getting is the content length
BYTE* pData = new BYTE[iFileSiz];
oFile.Read(pData, iFileSiz); // Reading file content
pData[iFileSiz] = '\0'; // Add last character as NULL
oFile.Close();

Now it will display the exact output as in file.

common error, since you have to declare the array 1 byte longer than the needed to have space for the terminating NULL:

BYTE* pData = new BYTE[iFileSiz + 1];

pData[ iFileSiz] = 0;