1. Nate Brunelle Today: Functions
CS1110
Nate Brunelle
Today: Functions

2. CS Majors Night What’s it like to be a CS major?
How do I declare a CS major?
Find out Tonight!
Rice 130
5pm

3. Questions?

4. Last Time
Strings, casting types

5. Function Like going to chipotle:
Enter with Your chipotle order in mind
Input
Instructions for how to turn your order into a burrito
Things can happen at chipotle that leave chipotle
Side effects
E.g. less money in your bank account
Leave with your burrito/bowl
output

6. Creating a function def name(“stuff we need to do the function”):
Indent
Things we are doing
return result

7. Functions Vocab Expression – Code that can become a value
Literal expression – an expression that cannot be simplified
Evaluate – turn an expression into a value
Argument – value/expression we send into a function
Parameter – name we use for input within a function definition
Attached to an argument when we use the function
Call/invoke – Use a function
Return – exit the function with a value
Return Value – the value we returned
Side Effect – things that a function does beyond returning something

8. Advice on functions You usually don’t want functions with side effects
Don’t use print, instead return a str
Don’t use input, instead use parameters
Good names
Usually an action phrase
Use docstrings
Define function in one file, use in another

9. Scope Scope- The are where a variable has meaning
Usually: variable is in scope when it is created onward.
Functions: variable is in scope when it is created until end of the function definition