Variables

A variable is a concept used in every programming language. Without variables, we can’t code.

A variable is used to remember a certain value so you can reuse it later on.

The assignment gives its value to a variable. The syntax is the following:

name = value

where to the left of the assignment symbol =, you write the name of your variable and to the right of the assignment symbol =, you write the value to be assigned.

Example

x = 8

result = 4 * 3

message = "hello"

Rules for naming a variable

• A variable name can be composed only by letters (uppercase & lowercase), numbers and underscore.
• A variable name can’t start with a number.
• Python is case sensitive so Age, aGe and age are three different variables.

Text vs Variable

To make sure that Python understands that we are writing text and not defining a new variable, we need to put apostrophe, quote or both around text.

Exercise

In the interpreter, type the following and observe the results:

• age = 14
• age
• age + 2
• age
• age = age + 2
• age

Question 1

Why did the value saved in the variable age change the second time you add 2 and not the first time?

• age = “age” * 2
• age

Question 2

Why is the text age saved in my variable age instead of a number?

>>>