Python Basics-

Introduction to python-

1. Python is a Simple programming language.
2. It is free & open source
3. It is a High level programming language.
4. Developed by Gudio van Rossum.
5. It is portable on all Operating systems.

Python Character Set-

1. Letters ( A-Z and a-z) means it is case sensitive languages in python Uppercase and Lowercase letters are different.
2. Digits (0-9).
3. Special symbols  (- + * / etc.)
4. White spaces (blank Space, tab, Carriage return, newline, form feed.)
5. Other character set - Python can access all ASCII and UNICODE characters .

Variables-

A variable is a name given to a memory location in a program. Meaning of variable is that its value can change (Vary).

Memory-

In memory of the Computer there would be a place of variables inside the memory and the value will be stored inside a variable.

example-

a=2

in mathematics a=2 (the value of a is equal to 2 but in Programming it means that the 2 is stored inside the variable a.)

Rules for Identifiers-

1. Identifiers can be combination of Uppercase  and lowercase letters, digits, or an Underscore(_)
2. An Identifier can not start with digit. So while Variable1 is valid ,  1Variable is not valid as a variable name. 
3. We can not use special symbols like (!, #, @,%,$ etc.)
4. identifier can be of any length. 

Variables name should be:

• Simple
• Short
• Meaningful

                                            Data Types

Main Data types in python are-

• Integers- (+ve, -ve, (negative infinity to positive infinity)) int
• Strings - (names, sentences, paragraphs) str " ", ' ', ''' '''.
• Float- (Decimal Values - 1.2, 2.0, 34.5)
• Boolean-(True and False.)
• None- Where we do not want to store any kind of value.

Keywords-

Python Keywords

Keywords in Python are reserved words that can not be used as a variable name, function name, or any other identifier.

List of Keywords in Python

Keyword	Description	Keyword	Description	Keyword	Description
and	It is a Logical Operator	False	Represents an expression that will result in not being true.	nonlocal	It is a non-local variable
as	It is used to create an alias name	finally	It is used with exceptions	not	It is a Logical Operator
assert	It is used for debugging	for	It is used to create Loop	or	It is a Logical Operator
break	Break out a Loop	from	To import specific parts of a module	pass	pass is used when the user doesn’t  want any code to execute
class	It is used to define a class	global	It is used to declare a global variable	raise	raise is used to raise exceptions or errors.
continue	Skip the next iteration of a loop	if	To create a Conditional Statement	return	return is used to end the execution
def	It is used to define the Function	import	It is used to import a module	True	Represents an expression that will result in true.
del	It is used to delete an object	is	It is used to test if two variables are equal	try	Try is used to handle errors
elif	Conditional statements, same as else-if	in	To check if a value is present in a Tuple, List, etc.	while	While Loop is used to execute a block of statements
else	It is used in a conditional statement	lambda	Used to create an anonymous function	with	with statement is used in exception handling
except	try-except is used to handle these errors	None	It represents a null value	yield	yield keyword is used to create a generator function

image source: Geeks for Geeks.

Keywords are reserved words in python. we cannot make keywords as variables. 

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