Python - Legal Variables

Creating a Legal Variable

We choose the names of our variables ourselves. But, there are some rules around creating a legal variable (a name we’re allowed to use).

Variable names may:

Use upper-case and lower-case letters
Use numbers
Use underscore characters (an underscore is the _ character)

There are rules to creating a legal variable

If we name our variables like this, we won’t have any problems:

>>> my_variable = 6
>>> string6 = 7
>>> YourVariable = 88

There are also things we can’t do. When naming variables, we cannot:

Use spaces
Start with a number

Look at what happens if we try to create an illegal variable:

>>> my variable = 6
  File "<stdin>", line 1
    my variable = 6
       ^^^^^^^^
SyntaxError: invalid syntax

>>> 2Variables = 6
  File "<stdin>", line 1
    2Variables = 6
    ^
SyntaxError: invalid decimal literal

Some Examples

Example	Legal?	Notes
a	yes	Lower-case is fine
time2go	yes	Numbers are fine
100ways	no	A variable cannot start with a number
A	yes	Upper-case is fine
fun_times	yes	Underscores are allowed and recommended where there would normally be a space
fun times	no	spaces are not allowed
FunTimes	yes	Capitalizing is fine
_count	yes	Starting with an underscore is fine
fun!	no	Characters other than numbers, letters, and underscores are not allowed

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