python-variables.md

Variables

Variables store values that can be looked at or changed later. You do not need to need to declare variable types before assigning them. However, you must initialize them before you call them. Different types of variables include:

Integer

An integer is a number that is not a fraction.

Examples: -1, 2, 105676, etc.

To define an integer, use the following syntax:

myint = 2

Floating Point

A number that has decimal values.

Examples: 1.0, -2.73, 0.66

To define:

myfloat = 7.3

or

myfloat = float(7)

With integers and floating points, you can perform basic math operations on them such as + - / * (with integers though, your answers will be rounded down to an integer).

String

Text surrounded by double or single quotes.

Examples: "Hello", 'World'

To define:

hello = "Hello"
world = "World"

You can also add strings together like this:

helloworld = hello + " " + world

This makes helloworld store the value "Hello World"

Or multiply a string with an integer to get a repeating string such as:

helloworld = "hello" * 6 + 3 * "world"

Which makes helloworld store the value "hellohellohellohellohellohelloworldworldworld"

PLEASE DO NOT SUBTRACT OR DIVIDE STRINGS

Character

A single symbol represented by a letter or number surrounded by single quotes.

Examples: 'A', '4', 'k'

To define:

mychar = 'h'

Single characters can be converted to their ASCII identifiers using the ord() function. Similarly, to convert an ASCII identifier back to a readable character, use the chr() function.

Python also has a useful type called a list. It's exactly what it sounds like, it's a way to store items in a non orderd way. Here's a quick example:

students = ["James", "Jim", "Bob", "Freyja the Norse mythological diety", "Sally"]

Elements of a list can be accesed via indicies, i.e. students[0] returns the first element. You can add to a list by .appending() something. Say I wanted to get a nice representation of all the students in my class:

Students enrolled in the School for Procrastination:
print ', '.join(students)

Another useful python type is the tuple, this is somewhat similar to the list, but the difference is that this is ordered. Not ordered in the sense that one is larger than the order, but think of a coordinate system, (x,y). That's how a tuple works.

battle_ship_location = ("B", 7) 
print "HIT"