Computer programming

Chapter 11 Exercises

Exercise 1: Write a simple program to simulate the operation of the grep command

on Unix. Ask the user to enter a regular expression and count the number

of lines that matched the regular expression:

$ python grep.py

Enter a regular expression: ^Author

mbox.txt had 1798 lines that matched ^Author

$ python grep.py

Enter a regular expression: ^Xmbox.

txt had 14368 lines that matched ^X-

$ python grep.py

Enter a regular expression: java$

mbox.txt had 4218 lines that matched java$

Exercise 2: Write a program to look for lines of the form

`New Revision: 39772`

and extract the number from each of the lines using a regular expression and

the findall() method. Compute the average of the numbers and print out the

average.

Enter file:mbox.txt

38549.7949721

Enter file:mbox-short.txt

39756.9259259