Before you keep reading...
Runestone Academy can only continue if we get support from individuals like you. As a student you are well aware of the high cost of textbooks. Our mission is to provide great books to you for free, but we ask that you consider a $10 donation, more if you can or less if $10 is a burden.
Before you keep reading...
Making great stuff takes time and $$. If you appreciate the book you are reading now and want to keep quality materials free for other students please consider a donation to Runestone Academy. We ask that you consider a $10 donation, but if you can give more thats great, if $10 is too much for your budget we would be happy with whatever you can afford as a show of support.
6.3. Naming Sets of Steps¶
How did abs and int get defined? By defining new procedures and functions, we can associate a name with a sequence of steps. Look at the program below. What do you think it will do when you press the Run button? Click Run and see what happens.
If you are wondering why the Run button didn’t seem to do anything, all that the program did was define the procedure
square which takes a
turtle as input. If we want to actually execute the program we need to create a turtle and call the procedure as shown in the next example.
In the above program, we DEFine the word
square to represent the Python statements that draw a square with a turtle. The
square procedure takes as input a
turtle that will be used to draw the square. Notice that the sequence of statements that are part of the
square procedure are indented. Python uses indention to show what statements belong to the procedure. When the indention stops with
from turtle import * it means that the new statements are not part of the procedure.
Notice that we defined the turtle procedure
def square (turtle): in the code above before we tried to call it
square(malik). This is required in Python, but not in some other programming languages.
6.3.1. Defining a Function¶
You define a function just like you define a procedure, but it will also
return a value as shown below.
To return a value from a function use the Python keyword
return followed by the value to return.
Check Your Understanding
See the video below for a hint on how to solve the next mixed up code problem.
The following code should define a procedure that draws a triangle, but it may be mixed up <i>and may contain extra (unused) code</i>. Drag the needed code to the right side in the correct order. <b>Remember that the statements in the procedure must be indented!</b> To indent a block drag it further right.
Discuss topics in this section with classmates.