Python 3.x Tutorial

Python

Python is an easy to learn, powerful programming language. It has efficient high-level data structures and a simple but effective approach to object-oriented programming. Python’s elegant syntax and dynamic typing, together with its interpreted nature, make it an ideal language for scripting and rapid application development in many areas on most platforms. Like Java, Python is also an interpreted programming language.

Python 3.x

Current tutorial will be focused on Python 3.x . Python 3.x is the present and future of the language.

Interpreter and Interactive shell

Python is an interpreted language and comes with an interactive shell.The interactive shell is interactive in the way that it stands between the commands or actions and their execution.

To fire up the interactive shell,type :

$ python3

in the terminal on your machine. If Python 3.x is succesfully installed on your machine, you should get such kind of output.

Python 3.5.1+ (default, Mar 30 2016, 22:46:26) 
[GCC 5.3.1 20160330] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 

type

>>> exit()

to quit the interactive shell.

Data types and variables

What is a variable ?

A variable is something which can change. A variable is a way of referring to a memory location used by a computer program.In many programming languages a variable is a symbolic name for this physical location. This memory location contains values, like numbers, text or more complicated types. We can use this variable to tell the computer to save some data in this location or to retrieve some data from this location.

How to create a variable in Python ?

You create a varible in Python by the the following syntax.

variable_name = variable_value my_variable = 90 Here we have created a variable with identifier name as my_variable and has assigned a value of 10 to it.

How to print something in Python ?

Python comes with a built in command print to print something on the interactive shell. type print("Hello world!") in the interactive shell, after this you'll see a message; Hello world!. Similarly to print the variable my_variable that we created before, type print(my_variable), you will see a message saying 90.

If something like a prompt comes up, similar like this :

Traceback (most recent call last):
NameError: name 'my_variable' is not defined

this means that we have not defined the variable my_variable in Python.