Variables

If we want to give a name to a variable, there’re some rules to follow.

1.       Variable name must be composed of upper case letters, lower case letters, digits and characters (underscore).

2.       Variable name must begin with a letter.

3.       Underscore character is also a letter.

4.       Variables with same meaning but, with different upper case & lower case letters are treated as two different variables.

Example:

THETEXT

thetext

theText

Given above three different variables.

5.       Variable name must not be any of Python’s reserved word.

NOTE

The PEP 8 – Style Guide for Python Code recommends the following naming convention for variables & functions in Python.

1.       Variable names should be lowercase with words separated by underscores to improve readability.

Example: my_variable

2.       Function names follow the same convention as variable names.

Example: my_function

3.       It’s also possible to use mixed case, but only in contexts where that’s already the prevailing style, to retain backwards compatibility with the adopted convention.

Example: myVariable

Keywords

Given below the reserved keywords in Python. They are reserved because we mustn’t use them as names, neither for the variables, nor functions. The meaning of the reserved word is predefined, and mustn’t changed any way.

['False', 'None', 'True', 'and', 'as', 'assert', 'break', 'class', 'continue', 'def', 'del', 'elif', 'else', 'except', 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is', 'lambda', 'nonlocal', 'not', 'or', 'pass', 'raise', 'return', 'try', 'while', 'with', 'yield']

A variable comes into existence as a result of assigning a value to it. Unlike in other languages, we don’t need to declare it in any special way. If you assign any value to a non-existent variable, the variable will be automatically created. We don’t need to do anything else.

The creation is very simple, just use the name of the desired variable then the equal sign (=) and the value you want to put into the variable.