#!/usr/bin/env python
#
# wc.py
#
# Count lines, words, and characters in a file.
#
# This 'wc.py' file was made executable with
#
#    $ chmod +x wc.py
#
# which lets it be executed from the command line
# without typing 'python', because of the 'unix shebang'
# first line of the file.
#
# If we have a file named 'plain.txt' with this in it
# 
#    This is a file full of text.
#    At least, I *think* that it is.
#    What do you think? Yes? No?
#
# then running the 
#    $ ./wc.py plain.txt
#    file    : plain.txt 
#    lines   : 3 
#    words   : 20 
#    letters : 89
#
# The filename is taken from the command line with the sys.argv list;
# see the source code below for more on how that works.
#
# Most unix systems have in fact a "wc" program already installed
# which does this same calculation :
#
#   $ wc plain.txt
#    3 20 89 plain.txt
#
# Jim Mahoney | Marlboro College | Sep 2014 | MIT License

import sys

filename = sys.argv[1]       # sys.argv is e.g. ['wc', 'file.txt']
file = open(filename, 'r')
lines = file.readlines()     # = ['first line\n', 'second line\n']

count_lines = len(lines)     # len() is the length function.
count_words = 0
count_letters = 0
for line in lines:
  count_letters = count_letters + len(line)
  count_words = count_words + len(line.split())  # split line at spaces

print " file    : {} ".format(filename)
print " lines   : {} ".format(count_lines)
print " words   : {} ".format(count_words)
print " letters : {} ".format(count_letters)