introduction
Python is a general-purpose high-level programming language.
Python was developed by Guido Van Rossum in 1989 while working at National
Research Institute in the Netherlands.
But officially Python was made available to the public in 1991. The official date of Birth for
Python is Feb 20th, 1991.
Python is recommended as the first programming language for beginners.
Ex 1: To print Helloworld :
Python
print("Hello World")Ex 2:
Python
1) a=10
2) b=20
3) print("The Sum:",(a+b))
The name Python was selected from the TV Show
"The Complete Monty Python's Circus", which was broadcasted on BBC from 1969 to 1974.
Where we can use Python:
We can use it everywhere. The most common important application areas are
For developing Desktop Applications.
For developing web applications.
For developing database Applications.
For Network Programming.
For developing games.
For Data Analysis Applications.
For Machine Learning.
For developing Artificial Intelligence Applications.
For IoT
WHICH COMPANIES USE PYTHON:
Internally Google and Youtube use Python coding.
NASA and Network Stock Exchange Applications developed by Python.
Top Software companies like Google, Microsoft, IBM, and Yahoo use Python.
Features of Python:
1) Simple and easy to learn:
2) Free and Open Source
3) High-Level Programming language
4) Platform Independent
5) Portability
6) Dynamically Typed
7) Both Procedure Oriented and Object-Oriented
8) Interpreted
9) Extensible
10) Embedded
11) Extensive Library
IDENTIFIERS
A Name in Python Program is called Identifier.
It can be Class Name OR Function Name OR Module Name OR Variable Name.
a = 10
Rules to define Identifiers in Python:
1. The only allowed characters in Python are
alphabet symbols(either lower case or upper case)
digits(0 to 9)
underscore symbol(_)
By mistake, if we are using any other symbol like $ then we will get a syntax
error.
cash = 10 (correct)
ca$h = 20 (wrong)
2. Identifier should not starts with a digit
123total (wrong)
total123 (correct)
3. Identifiers are case-sensitive. Of course, Python language is case sensitive language.
total=10
TOTAL=999
print(total) # output will come 10
print(TOTAL) #999
4) We cannot use reserved words as identifiers
Eg: def = 10
5) There is no length limit for Python identifiers. But not recommended to use too
lengthy identifiers.
RESERVED WORDS
In Python, some words are reserved to represent some meaning or functionality.
Such types of words are called reserved words.
Except for the following 3 reserved words, all contain only lower case alphabet symbols
True False None
Eg: a= true (wrong)
a=True (correct)
There are 35 reserved words available in Python.
True, False, None
and, or, not, is
if, elif, else
while, for, break, continue, return, in, yield
try, except, finally, raise, assert
import, from, as, class, def, pass, global, nonlocal, lambda, del, with
DATA TYPES
Data Type represents the type of data present inside a variable.
In Python, we are not required to specify the type explicitly. Based on the value provided,
the type will be assigned automatically. Hence Python is a Dynamically Typed Language.
Python contains the following inbuilt data types :
1) Int
2) Float
3) Complex
4) Bool
5) Str
6) Bytes
7) Bytearray
8) Range
9) List
10) Tuple
11) Set
12) Frozenset
13) Dict
14) None
Note: Python contains several inbuilt functions
1) type()
to check the type of variable
2) id()
to get the address of the object
3) print()
to print the value
In Python everything is an Object.
1) int Data Type:
We can use the int data type to represent whole numbers (integral values)
Eg: a = 10
type(a) #int
Note:
In Python, we have a long data type to represent very large integral values.
But in Python3 there is no long type explicitly and we can represent long values also by
using int type only.
We can represent int values in the following ways
1) Decimal form
2) Binary form
3) Octal form
4) Hexadecimal form
I) Decimal Form (Base-10):
It is the default number system in Python
The allowed digits are: 0 to 9
Eg: a =10
II)Binary Form (Base-2):
The allowed digits are : 0 & 1
Literal value should be prefixed with 0b or 0B
Eg: a = 0B1111
a = 0B123
a = b111
III) Octal Form (Base-8):
The allowed digits are : 0 to 7
The literal value should be prefixed with 0o or 0O.
Eg: a = 0o123
a = 0o786
IV) Hexa Decimal Form (Base-16):
The allowed digits are: 0 to 9, a-f (both lower and upper cases are allowed)
Literal value should be prefixed with 0x or 0X
Eg: a = 0XFACE
a = 0XBeef
a = 0XBeer
Note: Being a programmer we can specify literal values in decimal, binary, octal, and hexa
decimal forms. But PVM will always provide values only in decimal form.
a=10
b=0o10
c=0X10
d=0B10
print(a)10
print(b)8
print(c)16
print(d)2
Base Conversions :
Python provides the following in-built functions for base conversions
1)bin():
We can use bin() to convert from any base to binary
6) '0b10000'
2)oct():
We can use oct() to convert from any base to octal
We can use hex() to convert from any base to hexadecimal
2) Float Data Type:
We can use float data type to represent floating-point values (decimal values)
Eg: f = 1.234
types (f) float
We can also represent floating-point values by using an exponential form
(Scientific Notation)
Eg: f = 1.2e3 instead of 'e' we can use 'E'
print(f) 1200.0
The main advantage of exponential form is that we can represent big values in less
memory.
3) Complex Data Type:
A complex number is of the form
Eg: 3 + 5j
10 + 5.5j
0.5 + 0.1j
In the real part if we use int value then we can specify that either by decimal, octal,
binary, or hexadecimal form.
But imaginary part should be specified only by using the decimal form.
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