1. Intro to Programming Lecture 3
CIT 590
Intro to Programming
Lecture 3

2. Agenda Style More examples of functions Few notes about style
Variable names
The right way to end a program in python
comments
More examples of functions
Few notes about style
String slicing
Functions returning nothing
Code walkthroughs
cokeMachine.py
romanNumerals.py

3. Function style
Give functions reasonable names – sometimes might be hard to come up with an elegant name (see 3 for a possible solution)
Define functions in their own separate block – Python is super flexible and allows you to do this anywhere, but that affects readability
Put down a docString – a comment that explains what the function does. Triple quoted string to begin the function

4. Strings and string functions
name = ‘superman’
len(name) for length
name[0]
‘s’
Slicing – to get portions of a string (or list)
Positive indices name[1:3]
Includes the first index and excludes the ending index
Negative index means grab characters from the end
name[-1] is the last character

5. String and string functions
More slicing
name[1:]
name[:5]
name[:-5]
Copying a string
name[:] gives you all the character of the string
Looping through characters in a string
for ch in string:
The ‘+’ operator does concatenation for strings

6. Functions that return nothing
The NoneType
generally seen in functions with only output
used fairly often to initialize the value of a variable when you do not know what it might eventually hold