Opens a file channel.


   path STRING,
   mode STRING )
  1. path is the path to the file to open, can be NULL for stdin/stdout.
  2. mode is the open mode. Can be "r", "w", "a" or "u" (combined with "b" if needed).


The openFile() method can be used to open a file for reading, writing, or both.

When passing NULL as file name, the channel can be used to read and/or write to stdout or stdin, depending on the mode value.

When passing "<stderr>" as file name the standard error stream will be used. The application can then print messages to stderr (typically for batch programs). See Example 5: Writing to STDERR

The opening mode can be one of the following:
  • r: For read mode: reads from a file (standard input if path is NULL).
  • w: For write mode: starts with an empty file (standard output if the path is NULL).
  • a: For append mode: writes at the end of a file (standard output if the path is NULL).
  • u: For read from standard input and write to standard output (path must be NULL).
Any of these modes can be followed by b, to use binary mode and avoid CR/LF translation on Windows® platforms.
Note: The binary mode is only required in specific cases, and will only take effect when writing data.

If the opening mode is not one of the above letters, the method will raise error -8085

When you use the w or a modes, the file is created if it does not exist.

The method raises error -6340 sif the file cannot be opened.


CALL ch.openFile( "file.txt", "w" )

For a complete example, see Example 1: Using record-formatted data file.