Python Basics: Variables

Before we start with the actual topics lets have a general overview of Python

Python is a high-level and general-purpose programming language. Created by Guido van Rossum and first released in 1991. It is object-oriented and is dynamically typed. Python is meant to be an easily readable language and it often uses English keywords.

• Don't worry about all the technical terms as we dive deep into the language you will learn all the things.

• For the time being, you just have to know that:

      1. Python is a programming language, not a snake 🐍.
      2. It is the easiest language which anyone can learn in no time.
      3. And we will be using Python3 over Python2.
  

So let's program.

So let's type our first line of code. This is the code that every person in the world types when they start to learn to program.

   print("Hello, World!")
   print("Hope you are doing great!!!")

Here print is a function that is builtin, which takes anything written in the parenthesis and the quotes('' ") and prints it out on the screen.

Variables

Variables are the names you give to computer memory locations that are used to store values in a computer program OR Variables are containers for storing values. A variable is created the moment you first assign a value to it.

   Name= 'John'
   Age= 19
   Company= 'DreamLand'
   print(Name,Age,Company)

Output:

   John 19 DreamLand

As we can see in the above example Name, Age, and Company are three different variables all having different values. And when the variable names are called in the print function they are printed on the screen.

A variable can store only one value, as we continue through the program from top to bottom, if the same variable name is assigned with a different value the new value takes over the previous one, Variables do not need to be declared with any particular type and can even change type after they have been set

  x=19
  x='DreamLand'
  print(x)

Output:

   DreamLand

  x=19
  x=23
  print(x)

Output:

   23

Unlike, other programming languages, Python has no command for declaring a variable.

Naming of Variables

As we now know what are variables and how are they used now let's see some very important rules to create a valid Variable Name.

Rules for Naming of Variables are the same in almost all programming languages.

Rules:

• A variable name must start with a letter or the underscore character

• A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )

• A variable name cannot start with a number

• Variable names are case-sensitive (age, Age, and AGE are three different variables)

• There should be no spaces in the words

  #Valid Variable names
   myvariable1="DreamLand"
   my_variable="JaneDoe"
   _variable=17

  #Invalid Variable names
   invalid-variable='Mahendra'
   8variable=19
   invalid name='Doe'

When you run the above lines of code when the Python Interpreter reaches Invalid Variable names it raises a Syntax Error. Don't worry check your code correct it and carry on.

Shorthand for assigning multiple variables in one line

  fruit,color,cost= "Apple","Green",15.75
  print(fruit)
  print(color)
  print(cost)

Output:

Apple Green 15.75

• So this here finishes the basics of Variables hope you enjoyed the topic.

• Thanks for taking out your time and reading. 😄