.. _exercise_file_lab:

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File Exercise
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A bit of practice with files

Goal:
=====

Get a little bit of practice with handling files and parsing simple text.


Paths and File Processing
=========================

* Write a program which prints the full path for all files in the current
  directory, one per line

* Write a program which copies a file from a source, to a destination
  (without using shutil, or the OS copy command).

  - Advanced: make it work for any size file: i.e. don't read the entire
    contents of the file into memory at once.

  - This should work for any kind of file, so you need to open
    the files in binary mode: ``open(filename, 'rb')`` (or ``'wb'`` for
    writing). Note that for binary files, you can't use ``readline()`` --
    lines don't have any meaning for binary files.

  - Test it with both text and binary files (maybe jpeg or something of your choosing).


File reading and parsing
========================

Download this text file:

:download:`students.txt <../examples/file_exercise/students.txt>`

In it, you will find a list of names and what programming languages they have used in the past. This may be similar to a list generated at the beginning of this class.

Write a little script that reads that file, and generates a list of all the languages that have been used.

What might be the best data structure to use to keep track of bunch of values without duplication?

The file format:
----------------

The first line of the file is:

``Name: Nickname, languages``

And each line looks something like this:

``Jagger, Michael: Mick, shell, python``

So a colon after the name, then the nickname, and then one or more languages.

However, like real data files, the file is NOT well-formed. Only some lines have nicknames, and other small differences, so you will need to write some code to make sure you get it all correct.

Extra challenge: keep track of how many students specified each language.