Variables

Variables

• Variables are defined as reserved memory locations to store values.
• Based on the data type of a variable, the interpreter allocates memory and decides what can be stored in the reserved memory.
• Therefore, by assigning different data types to the variables, we can store integers, decimals or characters in these variables.

Rules for Naming Variables

• Variable names can contain letters,symbols like underscore ( __ ) and numbers,
• They begin with a letter not numbers.
• Both uppercase and lowercase letters are different
• Keywords cannot be used as variable names.

Example for valid identifier
abc, xy12, good_start

Example for non-valid identifier
12xy, x$y

Assigning Values to Variables

• Python variables do not need explicit declaration to reserve memory space.
• The declaration happens automatically when we assign a value to a variable.
• The equal sign = is used to assign values to variables.
• The operand to the left of the = operator is the name of the variable and the operand to the right of the = operator is the value stored in the variable.

example:

counter=100# An integer assignment
miles=1000.0# A floating point
name="John"# A string

Multiple Assignment

Python allows us to assign a single value to several variables simultaneously. Example

a = b = c =1

Here, an integer object is created with the value 1, and all the three variables are assigned to the same memory location. We can also assign multiple objects to multiple variables. For example

    a, b, c =1,2,"john"

Here, two integer objects with values 1 and 2 are assigned to the variables a and b respectively, and one string object with the value "john" is assigned to the variable c.