Game Development Reference
In-Depth Information
def
Statements
The def statement isn't a call to a function named
displayIntro()
. Instead, the
def
statement means we are creating, or
defining
, a new function that we can call later in our
program. After we
define
this function, we can call it the same way we call other functions.
When we
call
this function, the code inside the def-block will be executed.
We also say we define variables when we create them with an assignment statement. The
code
spam = 42
defines the variable
spam
.
Remember, the def statement doesn't execute the code right now, it only defines what
code is executed when we call the
displayIntro()
function later in the program.
When the program's execution reaches a
def
statement, it skips down to the end of the def-
block. We will jump back to the top of the def-block when the
displayIntro()
function is called. It will then execute all the
print()
statements inside the def-block. So
we call this function when we want to display the "You are on a planet full of dragons..."
introduction to the user.
When we call the
displayIntro()
function, the program's execution jumps to the
start of the function on line 5. When the function's block ends, the program's execution
returns to the line that called the function.
We will explain all of the functions that this program will use before we explain the main
part of the program. It may be a bit confusing to learn the program out of the order that it
executes. But just keep in mind that when we define the functions they just silently sit
around waiting to be called into action.
Defining the
chooseCave()
Function
11. def chooseCave():
Here we are defining another function called
chooseCave
. The code in this function
will prompt the user to select which cave they should go into.
12. cave = ''
13. while cave != '1' and cave != '2':
Inside the
chooseCave()
function, we create a new variable called
cave
and store a
blank string in it. Then we will start a
while
loop. This while statement's condition
contains a new operator we haven't seen before called
and
. Just like the
-
or
*
are
mathematical operators, and
==
or
!=
are comparison operators, the and operator is a
boolean operator.