Outline for October 6, 2021

Reading: §6.1–6.8}
Due: Homework 1, due October 6, 2021

1. Sequences
   1. Sequences are a series of values in a particular order
   2. In Python predominantly strings and lists but also sets and tuples

2. Strings
   1. Sequence of characters (characters are strings of length 1)
   2. Strings are immutable; really important for functions

3. Basic string operations
   1. +, concatenation for strings
   2. *, repetition repeats given value
   3. len() returns length of sequence
   4. s in str returns True if s is a substring of str, False otherwise

4. Indexing, var[position]
   1. Count from 0 to len(var)-1
   2. Position can be a negative number to count from right

5. Assignment with indexing doesn’t work as strings immutable x = ’hEllo’; x[1] = ’e’ produces an error

6. Slicing, var[start:end]
   1. Value at index end not included in slice
   2. If omitted, starting value defaults to 0 and ending value defaults to last index + 1
   3. Can use negative index

7. Looping over strings: for i in str

8. Example program [strstuff.py]

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ECS 235A, Computer and Information Security Version of October 4, 2021 at 11:36PM

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