CPSC120B - Day 13 Notes

No Cool Computer Science Thing of the Day

No Reading Questions

No Quiz

Function Scope

Variables created inside a function only exist in a function

They are local to the function

def do_something():
    x = 1
do_something()
print(x)

Variables created outside a function can be read inside the function
They are global variables
This is desirable when working with constant variable, otherwise discouraged
```
x = 1
def do_something():
    return x + 1
print(do_something())
```
Variables created outside a function can not be modified inside the function
Instead it creates a new variable inside the function with the same name as the variable outside
The local variable shadows the global variable
This is desirable, it allows you to name variables inside of functions without having to worry about the function affecting code elsewhere
```
x = 1
def do_something():
    x = 2
do_something()
print(x)
```
These same rules apply to parameters
This is common when variables are used as the input to a function
```
x = 1
def do_something(x):
    x = 2
do_something()
print(x)
```

Functions Calling Functions

Functions can call other functions

def do_something(x):
    b = x + 1
    return b

def do_something_else(x):
    a = do_something(x)
    c = a - 1
    return c

print(do_something_else(2))

Lab

lab13