Python Variables

Python Variables

As the name suggests, variable is something that can change. In Python, variables are containers that store data values.  More specifically, variables are reserved memory locations that give data to the system to process the code.

A variable can also be seen as a symbolic representation for the memory that was reserved by the data. Another great thing about Python is that the value as well as the data type of the variable can be changed during the code execution.

Example

Python variable: value & data type changes during the execution of the code

As you can see in the output, the data type of the variable was changed in the same code execution. The Python function “type” is used to get the information about the data type of the variable.

Python Variable Declaration

When we declare a variable, we bind it to a data type. There are some rules you have to follow while declaring a variable otherwise the interpreter will give you an error. The rules are as follows: –

  • The first character in the variable name can be a small, a capital letter or an underscore (“_”) but it cannot be a number.
  • Characters following the first letter can be any alpha-numeric character like numbers, alphabets, etc.

Python is a case sensitive language; therefore, x and X will be different for the interpreter and will show an error if the value stored in the capital letter is called by the small letter counterpart.

Example

Python variable case sensitive

Data Types in Python

There are 5 standard data types in Python: –

  • Numbers
  • Strings
  • Lists
  • Dictionary
  • Tuple

It is an important thing to know right now for the later part of this tutorial page.

Multiple Declaration

Python lets you declare multiple variables in a single statement. If you want to make your code shorter, this is a great way to do it.

Example

Python variable multi declaration single statement

Taking Inputs

You can also assign a same value to multiple variables in the same line of code.

Example

Python variable same value assigned

Variable Manipulation

In Python, “print” is used quite often to output variables. Two similar data types can be combined using the “+” operator to give a single data unit.

Example

Python variable similar data type concatenation

But what happens when you try to add a number and a string?

Example

Python variable: Number concatenated with string Error

Types of Python Variables

There are 2 types of variables in Python. These are –

  1. Global variable
  2. Local variable

1. Global Variable

A variable which is created outside of a function is called a Global variable.  You can use this type of variable anywhere in the code.

Example of Global variable - 1

Python global variable

Example of Global variable - 2

Python global variable

2. Local Variable

A variable that is only present exclusively for a particular function in which it was created, then that variable is a Local variable.

Example

python local variable

If you want to make a local variable global, you can put the “global” keyword before the variable name in prior to declaring the variable.

Example

Python make local variable global

In this case, Python won’t show any error and will just print the output twice. Also, you can change the value of a global variable inside a function by adding “global” keyword before the variable inside the function.

Deleting a Variable

Python also allows you to delete a variable by using the command “del”

Example

Python delete Variable

As you can see, once you delete a variable and when we tried to print it, interpreter gives an error.

Bonus Tips

  • Always keep the variable name short and meaningful.
  • Decide carefully whether you want to declare a variable as a Local variable or a Global variable.

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