Classes and Methods

GPL provides the File built-in class for managing files and directories. Table 19-34 summarizes the various methods available.

Table 19-34: File Class
File Class Member	Type	Description
File.ComputeCRC	Shared Function	Returns a CRC check code computed by reading though a file. Used to verify that a file has not been corrupted.
File.ComputeLength	Shared Function	Returns the length of a file computed by reading through a file and counting the bytes. Used to verify that a file has not been corrupted.
File.Copy	Shared Method	Copies a single file on devices like the flash disk and ROMDISK.
File.CreateDirectory	Shared Method	Creates a directory including any undefined directories in its path.
File.DeleteDirectory	Shared Method	Deletes a single directory, if it is empty.
File.DeleteFile	Shared Method	Deletes a single file.
File.GetDirectories	Shared Method	Returns an array of strings containing the names of directories in a directory.
File.GetFiles	Shared Method	Returns an array of strings containing the names of files in a directory.
File.Length	Shared Function	Efficiently returns the length of a file based on its directory entry.

GPL provides two built-in classes for accessing streams: StreamReader and StreamWriter. See Table 19-35 and Table 19-36.

Table 19-35: StreamReader Definitions
StreamReader Member	Type	Description
New StreamReader	Constructor Method	Opens a file or serial port device for reading.
streamreader_obj.Close	Method	Closes a file or device.
streamreader_obj.Peek	Method	Reads a single byte but does not remove it from the input stream.
streamreader_obj.Read	Method	Reads a single byte and removes it from the input stream.
streamreader_obj.ReadLine	Method	Reads a line of bytes terminated by LF, CR, or CR-LF.

Table 19-36: StreamWriter Defnitions
StreamReader Member	Type	Description
New StreamWriter	Constructor Method	Opens a file or serial port device for writing.
streamwriter_obj.AutoFlush	Property	If True, automatically flushes output after every write.
streamwriter_obj.Close	Method	Closes a file or device.
streamwriter_obj.Flush	Method	Forces any pending output to occur immediately.
streamwriter_obj.NewLine	Property	Defines the line terminator characters that are appended to output by WriteLine.
streamwriter_obj.Write	Method	Writes a string or number to the output stream with no line terminator.
streamwriter_obj.WriteLine	Method	Writes a string or number to the output stream followed by a line terminator.

The same methods are used for accessing both files and serial ports. The major differences between the two are:

Serial ports are normally used for communications, but files are used to save and retrieve data.
Data read from files is normally available immediately, but you may need to wait to receive data from a serial port.
Files have an "end of file", but serial port data can continue indefinitely.
Data written to files is normally buffered for efficiency, but serial port communications are often time-critical so the output is not buffered.

GPL also provides a built-in class for performing output to the serial console or to the GDE console window. See Table 19-37.

Table 19-37: Console Class Definitions
Console Class Member	Type	Description
Console.Write	Shared Method	Diagnostic method that writes a number or a string to the console.
Console.WriteLine	Shared Method	Diagnostic method that writes a number or a string to the console, followed by a line feed (LF) character.