Python chap 2 (Basic Syntax:Hi friends this is the continuation of previous post so i kindly request you to read that before this post. As this blog is also prepared for beginners so i advice you that you don't need to by-heart this lessons just read and understand it if you have any doubt ask in the comment section )

                       

   Start with Interactive Mode 

friends we are here to learn the python 3 it is somewhat different from python 2  lets begin. If the commands are read from a tty the interpreter is said to be in interactive mode .Interactive mode is a command line shell which gives immidiate feedback for each statement and while running previously fed statements in active memory The interpreter prints a welcome message stating its version number and a copyright notice before printing the first prompt:

$ python3.6
 Python 3.6 (default, Sep 16 2015, 09:25:04)
[GCC 4.8.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

now type the following code 

>>> print ("HELLO, WORLD!")

This produces the result as

HELLO, WORLD!

Scripting Mode

On Installing python you will get a default python IDE "IDLE" lets write some code now in the Invoking the interpreter with a script parameter begins execution of the script and continues until the script is finished. When the script is finished, the interpreter is no longer active. Let us write a simple Python program in a script. Python files have extension .py. Type the following source code in a nads.py file

print("HELLO, WORLD!")

you should have Python interpreter set in PATH variable.to know about how to set python interpreter view my previous posts Now, try to run this program as follows

$ python nads.py

This produces the following result

HELLO, WORLD!

Python Identifiers

Python identifier is a name used to identify a variable, function, class, module or other object(all of this will be explained in the coming lessons).many other programming languages insist on having every identifier used in code have type information declared for it.but python doesn't need so. An identifier starts with a letter A to Z or a to z or an underscore (_) followed by zero or more letters, underscores and digits (0 to 9).

                          Python does not allow punctuation characters such as @, $, and % within identifiers. Python is a case sensitive programming language. Thus, Atom and atom are two different identifiers in Python.
 The naming conventions for python are

• Class names start with an uppercase letter. All other identifiers start with a lowercase letter.
• Starting an identifier with a single leading underscore indicates that the identifier is private.
• Starting an identifier with two leading underscores indicates a strongly private identifier.
• If the identifier also ends with two trailing underscores, the identifier is a language-defined special name.

here is an example of python identifiers:

name_value = "this is a string value "
num_value = 458

RESERVED WORDS

reserved words are keywords those words which can't be used as a variable name, function name or any other identifier. They are used to define the syntax and structure of the Python language. In Python, keywords are case sensitive.

and	exec	not
assert	finally	or
break	for	pass
class	from	print
continue	global	raise
def	if	return
del	import	try
elif	in	while
else	is	with
except	lambda	yield

LINES AND INDENTATION

A python programme is composed of a sequence of logical lines each made up of one or more physical lines of codes in python end of a physical line marks the end of the statement in other languages like java there is semicolon added at last to end of the statement

                     In python there is no curly brackets {} like in other languages to indicate blocks of code for class and functions definition or flow control . Here in python they uses indentation to indicate the block of code the number of spaces is variable but the different statements within the  code blocks must be at same amount of space like in the code given below

if True:
    print("true") 
else :
    print("false")

 

that's all for this post guys More on this part will be discussed in the next post

 

 

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