8-5

#! /usr/bin/env python3.2
# -*- coding: utf-8 -*-

# main.py
""" Task: Exercise 8.5
    Write a program to read through the mail box data and when you find line
    that starts with “From”, you will split the line into words using the split
    function. We are interested in who sent the message which is the second
    word on the From line.

    From stephen.marquard@uct.ac.za Sat Jan 5 09:14:16 2008

    You will parse the From line and print out the second word for each From
    line and then you will also count the number of From (not From:) lines and
    print out a count at the end.
    This is a sample good output with a few lines removed:

    python fromcount.py
    Enter a file name: mbox-short.txt
    stephen.marquard@uct.ac.za
    louis@media.berkeley.edu
    zqian@umich.edu

    [...some output removed...]

    ray@media.berkeley.edu
    cwen@iupui.edu
    cwen@iupui.edu
    cwen@iupui.edu
    There were 27 lines in the file with From as the first word
"""

# test.txt is equal to mbox.txt, but added following 3 lines somewhere:
"""
>>> The next line fails with the original code:
From xyz
>>> because of there are more than one, but less than two words...
"""

''' Functions '''
def enterFileName():
    """
    The user has to enter a filename.
    Returns fileName
    """
    fileName = None
    while fileName == None:
        # Enter filename
        try:
            fileName = input("Enter the filename: ")
        except:
            print("Invalid input!")
            continue
    return fileName
# End of enterFileName()

''' Main '''
fileName = enterFileName()
try:
    fhand = open(fileName)
except IOError:
    print("No such file available!")
    exit()
count = 0
for line in fhand:
    words = line.split()
    # print('Debug:', words)
    if len(words) >= 2 and words[0] == 'From':
        try:                # Additional guard
            print(words[1])
            count += 1
        except IndexError:
            continue
print("There were " + str(count) +
      " lines in the file with From as the first word")
try:
    fhand.close()
except:
    exit()