Input
#####

Comefrom0x10 programs can receive input from all the normal places, standard input, files and the command line.

Command-line arguments
**********************

The global ``argv`` stores command-line arguments to Cf0x10 programs. This example echoes its command line arguments::

   # In the file echo.cf0x10
   argv

Invoked thus:

.. code-block:: shell
   
   cf0x10 echo.cf0x10 hello world

Prints ``hello world``.

Standard input
**************

This example prompts for input from the user and exits when the user enters a blank line::

   prompt
       comefrom echo
       'Type something: '...
       stdin = ''

   echo
       comefrom stdin if stdin
       'You typed "' stdin '"'

       # jumps back to prompt

Input is blocking and line-buffered. Changing the ``stdin`` global causes the program to wait for input, so it actually pauses at the line ``stdin = ''``, until stdin is set.

Each line automatically gets its trailing newline dropped (automatically chomped, in Perl-speak).

End-of-file (EOF) sets stdin to ``undefined``, so a Cf0x10 program can trivially detect the end of piped input.

Files
*****

Setting the ``read_path`` global causes a read from the given path, whose contents will be stored in the ``file`` global. This cat program reads a single file and prints its contents to standard out::

   read_path = argv
   file

Setting the ``write_path`` global causes the contents of the ``file`` global to be written to ``write_path``. This program writes "Hello, world" to a path given on the command line::

   file = 'Hello, world'
   write_path = argv

Because Cf0x10 has no binary data type, files are always encoded and decoded as UTF-8.