Python (Basics) – Comments,Indentation,Built-in Number Data types and Expressions

Comments,Indentation,Built-in Number Data types and Expressions in Python

1. Comments in Python

Comments are statements given by programmer for better understanding of programs.They are non executable statements.
Comments are of two types:

Single line comments

Single line comments are given by using ‘#’ symbol before writing statement.

EXAMPLE

#code to display itvoyagers
print('itvoyagers')

Multi line comments

Multi line comments are given by using opening and closing “”” “”” or ”’ ”’ symbol(triple quotes) before and after writing statements.

EXAMPLE

"""code to display itvoyagers and 
to show example of multiline comments"""
print('itvoyagers')

Indentation in Python

Other programming languages uses opening and closing braces {} to define a block of statement.
This braces are replaced in python with indentation.
Indentation is important both IDLE and Script mode.
Indentation can be given as four spaces or one tab key.

EXAMPLE

for i in range(5):
    print('itvoyagers')
else:
    print("sorry range exceeded")

Note: in above example if indentation is not given then it may lead to indentation error

Built-in Number Datatypes in Python

Various classes like integer,floating point,long and complex indicates numeric values.
These can be defined as int, float, long and complex.

a. Integer (class int)

Integers can be positive or negative and are of unlimited size in Python.

EXAMPLE
143,-426

>>> 82-951+6
-863
>>> 1500087521651235122453210452104520+9
1500087521651235122453210452104529
>>> 2**945
297403381695556612559612499629980112026252040331878891811154371863188131432080874709033662899231270117959744758038594610090917049108981141558166116220478925156594168089491974788537281966859547374047839156470287441213549741375576017631419788069731616602409021090828782564753069762936832
>>> len(str(2**945))
285

Note: Above examples shows that integers are of unlimited size in python

b. Floating Point Numbers(class float)

Floating point numbers can be positive or negative which comes with decimal point and an optional exponent (e or E)
Floats are 64-bit double precision floating point numbers.

EXAMPLE
10.2,-9.6,3e4,-3E-4

>>> 5.42*-4e5
-2168000.0
>>> import random
>>> random.random()
0.5292462067367842
>>> 2.0**945
2.974033816955566e+284

c. Booleans (class bool)

Boolean values like True and False is given.
Here T and F are capitalized in boolean values.
In Python 0,None and empty value such as empty string “”,”,empty list [],empty dictionary {},empty tuple() etc are considered as False and anything apart from this is considered as True.

EXAMPLE

>>> True + 5
6
>>> False + 10
10
>>> True-False
1
>>> 50==50
True
>>> 50==80
False

d. Complex Numbers(class complex)

Complex numbers have two parts i.e. real and imaginary.
Real can be any integer and imaginary part is having ‘j’ as suffix
eg.(3+2j)

EXAMPLE

>>> 3+2j *8
(3+16j)
>>> 3+2j+5
(8+2j)
>>> 3+2j-2
(1+2j)
>>> k=9+5j
>>> k.real #to get real number
9.0
>>> k.imag #to get imaginary number
5.0

Expressions in Python

An expression is a combination of values,variables and operands.
EXAMPLE

>>> p=120
>>> p+60
180
>>> 12
12
>>> 8+(2-1)*9
17
>>> 



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