Outline for November 7, 2023

Reading: §14, 12, 13
Due: Homework 3, due November 9, 2023

1. Useful abbreviations in patterns
   1. \d matches any digit; same as [0-9]
   2. \s matches any space character; same as [ \t\n\r\f\v]
   3. \w matches any alphanumeric character and underscore; same as [a-zA-Z0-9_]
   4. \D matches any character except a digit; inverse of \d
   5. \S matches any character except a space character; inverse of \s
   6. \W matches any character except an alphanumeric character or underscore; inverse of \w
   7. \b matches a word boundary — a word is a sequence of alphanumeric characters

2. “Raw” string notation: backslash not handled specially; put “r” before string

3. Example of floating imprecision [roundoff.py]

4. Character/integer conversions [chr.py, ord.py]
   1. Cæsar cipher (shift cipher) [caesarenc.py, caesardec.py]

5. Reading a URL [geturl.py, geturl2.py, geturl3.py]
   1. Opening a URL
   2. Reading the page as a string
   3. The role of decode() [geturl-nd.py]

6. A program to print links in web pages [urlpat.py, urlpat2.py]

Matt Bishop Office: 2209 Watershed Sciences Phone: +1 (530) 752-8060 Email: [email protected]

ECS 235A, Computer and Information Security Version of November 2, 2023 at 11:28PM

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