API AppendToLog

Private Function AppendToLog(ByVal lpFileName As String, ByVal sMessage As String) As Boolean
'appends a string to a text file. it's up to the coder to add a CR/LF at the end
'of the string if (s)he so desires.
 'assume failure
 AppendToLog = False
 
 'exit if the string cannot be written to disk
 If Len(sMessage) < 1 Then Exit Function
 
 'get the size of the file (if it exists)
 Dim fLen As Long
 fLen = 0
 
 If (Len(Dir(lpFileName))) Then
 fLen = FileLen(lpFileName)
 End If
 
 'open the log file, create as necessary
 Dim hLogFile As Long
 hLogFile = CreateFile(lpFileName, GENERIC_WRITE, FILE_SHARE_READ, ByVal 0&, _
   IIf(Len(Dir(lpFileName)), OPEN_EXISTING, CREATE_NEW), _
   FILE_ATTRIBUTE_NORMAL, 0&)
 
 'ensure the log file was opened properly
 If (hLogFile = INVALID_HANDLE_VALUE) Then Exit Function
 
 'move file pointer to end of file if file was not created
 If (fLen <> 0) Then
 If (SetFilePointer(hLogFile, fLen, ByVal 0&, FILE_BEGIN) = &HFFFFFFFF) Then
 'exit sub if the pointer did not set correctly
 CloseHandle (hLogFile)
 Exit Function
 End If
 End If
 
 'convert the source string to a byte array for use with WriteFile
 Dim lTemp As Long
 ReDim TempArray(0 To Len(sMessage) - 1) As Byte
 
 For lTemp = 1 To Len(sMessage)
 TempArray(lTemp - 1) = Asc(Mid$(sMessage, lTemp, 1))
 Next
 
 'write the string to the log file
 If (WriteFile(hLogFile, TempArray(0), Len(sMessage), lTemp, ByVal 0&) <> 0) Then
 'the data was written correctly
 AppendToLog = True
 End If
 
 'flush buffers and close the file
 FlushFileBuffers (hLogFile)
 CloseHandle (hLogFile)
 
End Function