CPSC120B - Day 10 Notes

We can define our own named code

def draw_something():
    turtle.forward(100)
    turlte.left(90)

Execute the function just like other functions, draw_something()
Note, order matters, you can’t use it until you have defined it, just like a variable

Note that the previous example creates a new turtle every time it is executed
We can fix this if by having the function share the same turtle across multiple executions.
To do this we need to give the function input, the turtle to use

Parameters are variables with a value set outside of the function

def draw_something(dist):
    turtle.forward(dist)
    turtle.left(90)

Now, it can be called like this
```
draw_something(10)
```
This is much like the turtle functions we have already used… turtle.forward(100), the 100 is the input to the function, it changes the behavior of the function
The names of the inputs, in the function definition, are called parameters
The names of the inputs, in the function call, are called arguments

If a function has multiple parameters, then the order of the arguments is the same

def draw_something(dist, angle):
    turtle.forward(dist)
    turtle.left(angle)

draw_something(10, 20)

In this case, dist has the value 10 and angle has the value 20 because the parameter dist is before the parameter angle

For the lab today you will need to draw images using the grahpics module
The graphics module can only draw gif images
To find a gif do a google image search and filetype:gif to your search terms
Put the image in the same directory and you .py file and the graphic.py file
Draw an image with the draw_image function
```
graphics.draw_image('ball.gif', 0, 0)
```
The first argument is the name of the image file, don’t for get the quotes
The second and third arguments are the x and y coordinates of the center of the image

CPSC120B
Fundamentals of Computer Science