6. Data Types, Variables and Input

You will learn about:

• Data types
• Variables 
• User Input

Activity 5.2

Data types

Use the “type” function to find out the data types for these values.

>>>type("Fred")

>>>type(198)

>>>type(88.9)

>>>type(True)

>>>type(False)

Hint: Remember that True and False must start with a capital letter.

Activity 5.3

The type function returns the data type of an expression.

For each of these expressions, first predict the data type then use the type command to see if your prediction was correct.

Expression	Predicted data type	Type command	Result
“hello world”		type("hello world")
False		type(False)
15		type(15)
35.6		type(35.6)
-999		type(-999)
“15”		type(“15”)
“False”		type(“False”)
True		type(True)
0.001		type(0.001)

Activity 5.4

The interactive shell is a useful place to explore variables.

•

Copy and run this code in the interactive shell.

myName="Fred Smith"

myAge=14

print(myName,myAge)

•

Create a variable called myName and assign it to your name.

•

Create a variable called myAge and assign it to your age

•

Create a variable called myEyes and assign it to your eye colour.

•

Create a variable called myHeight and assign it to your height.

•

Write the commands to display on the screen your name, age, eye colour and height.

Hint: Remember that a single ‘=’ is used to assign a value to a variable.  

Activity 5.5

Variable names

A programmer is trying to decide on a valid name for a variable that represents a house number.

•

Which of the following variable assignments are valid? Why are the others not valid?

	Valid or invalid variable name?	Reason why not valid
8HouseNumber = 288
houseNumber = 288
house Number = 288
house_number = 288
import = 288

•

What type of error do you get when using an invalid variable name?

Activity 5.6

•

Copy and run this code and explain the result.

# Programmer Amy Jones 12/8/2013

# adds two numbers

numberOne=15

numberTwo=23

answer=numberOne + numberTwo

print("The answer is “,answer)

•

Amend the program to add another variable called numberThree. Assign the value 76 to this variable. The program should all up all three numbers and print the result.

Activity 5.7

Data types in Python

Complete this table to describe the four data types.

Data type	Python abbreviation	Explanation	Example
integer	int
string	str
float	float
boolean	bool

Hint: Quotation marks are used to show the start and end point of a string, e.g. “this is a string”.