P

1) High level prog. language

2) Python is work quickly and integrate system more efficiently.
3) Python are simple and easy, portable build in data structure and open sources.
4) Python is high level interpreted, interactive and object oriented scripting language.
5) Python is designed to high readable.

::Interpreted::  
1) Python is processed at run time by interpreter.
2) Not need to compiler your program before executing it.

::Interactive:: You can actually sit at a python prompt and interact with interpreter directly to write your program.

::Object Oriented::  Python supports objects oriented technique of    programming that encapsulates code within object.

Characterizes:-
1) Python supports functional, structured program as well as OOP's.
2) Python is used as Scripting language.
3) It can be compiled to Byte code for building large application.
4) It provides high level dynamic data type and support automatic garbage collection.

Application of Python:-
1) Easy-to-learn:- Python has few keywords, structures and and defined syntax.
2)Easy-to-read:- Python code is more clearly defined and visible to the eyes.
3)Easy-to-maintain:- Python source is fairly easy to maintain.
4)Portable: Python can run on a wide variety of hardware platform and same interface on all platform.

Command-line Option's:-
-d Provides debug input
-o Generate optimized Byte code
-s Do not run import site to look   
-x Disable class built in exception
-c cmd Run python script sent in cmd string
File Run python script from given file

Keywords:-

Its is reserved words that can't change during execution.

if

else

while

and 

assert

raise 

yield

break

class

continue

def

del

return

elif

except

exec

finally

for

try 

form

global

import

in

is

while

lambda

not 

or

pass

print

with

Notes:-

1) Python provides no-braces to indicate block of code for class and function,

2)Comments in python that # (hash) is not inside string being a comments.

command line arguments:-

Python enable you to do commands line arguments with -h-

$python -h                         

-c cmd :prog passed in as string   

    -d :debug output               

    -E :Ignore environment variable

    -h :print help message and exit

Variable

• Variable is reserved memory location to store value.
• Data type of variable, the interpreter allocated memory and decides, what can be stored in reserved memory.

Data type

1) Number

   a) int

   b) long

   c) float

   d) complex

2) String
3) List
4) Tuple
5) Dictionary

(1)Number: Stored numeric value's, number object are created,                   when you assign a value.
           var1=20
           var2=10

(2)String: Set of character's represented quotation marks.
              
         e.g HelloWorld 
          0-H 
          1-e
          2-l 
          3-l
          4-o
          5-W
          6-o
          7-r
          8-l
          9-d
          10-\0 null pointer

#program about string
#! /user/bin/python
str="Hello World"
print str-------print complete string
print str[0]----print first character  H
print str[2:5]---print 3rd to 5th char llo
print str[2: ]---print 3rd starting to end lloWorld
print str *2-----print two line's helloWorld HelloWorld
print str +"Test"--Print concatented string---HelloWorld Test

* asterisk sign:- string is repetition operator

+ plus     sign:- string concatenation operator

(3)List:-

•  A list contain item's separated by common and enclosed within square brackets [].
• List are similar to array in C-language.
• Diff between array ad list is stored different data type together.
• Value stored in list can be accessed using Slice operator [] and [:] with staring at 0.

#Program about list

#!/user/bin/python

list=['Mohit',8927,3.57,'Vicky',70.2]

tinylist=[123,"Vicky"]

print list-------Print complete list

print list[0]----print first element Mohit

print list[1:3]--print starting from 2rd to 3rd--8927,3.57

print list[2: ]--print element starting from 3rd element 

print tinylist *2--print list two times

print list +tinylist---Print concatenated list

(4)Tuple:-

• Its is similar to list.
• Tuple consists of number of value separated by commons.

#! /usr/bin/python
tuple=('abcd',786,2.23","Mohit",70.2)
tinytuple=(123,'Mohit')
print tuple      #print completed list
print tuple[0]   #print 1st element ---abcd
print tuple[1:3] #print staring 2rd till 3rd--7862.23
print tuple[2: ] #print element starting from 3rd
print tinytuple *2     #print list two times
print tuple +tinytuple #print concatenated lists  

Diff between Tuple & List:
>> Tuple are enclosed in brackets [] and their size can be changed and tuple can be though read only lists.
>> List are enclosed in parentheses () and can't changed.

(5)Dictionary:-

• Python dict are kind of hash table type.
• They work like associative arrays.
• Dict key can be almost python type,but are usually number of string.
• Dict are enclosed by curly braces {} and value can assigned & accessed using square braces [].

#program about dict
#!/usr/bin/python
dict={}
dict['one']="This is One"
dict[2]="This is Two"
tinydict={'name':'Mohit','code':6734,'dept':'IT'}
print dict['one'] #print value 'one' key---This is one
print dict[2]     #print value '2' key----This is two
print tinydict    #print completely dictionary
print tinydict.key()    #print all the key
print tinydict.values() #print all the value

Data type Conversion

• To convert between type's, you simply use type name of a function.
• Build in function to perform conversion from one data type to another.
• Its is return a new object representing the converted value.

• int (x[,base])   converts x to integer and base specifies base if x is string.
• long(x[,base]) converts x to long integer and base specific base,if x is string.
• float(x)           convert x to floating point number
• complex(read[,imag]) Creates a complex number
• str(x) Converted object x to string represent 
• repr(x) Converted object x to expression string
• eval(str) Evaluates string and return object
• tuple(s)converted s to tuple 
• list(s)  converted s to list
• set(s)  converted s to set
• dict(d) Created a dict, d must be a sequence of(key,value) tuple's.
• chr(x)  Coverts integer to characters
• ord(x)  Coverts integer to integer to unicode character
• hex(x) Converts integer to hexadecimal
• oct(x)  Converts integer to Octal string

Operator's

(1)Arithmetic + - * / o/o--module **--Exponent  //--floor_division
(2)Relational == != <> >< >= <=
(3)Assignment = += -= *= /= %= **= //=
(4)Logical    & / ~ ^ << >>
(5)Bitwise    AND OR NOT
(6)Membership:- is a sequence such as string,list and tuple
   in evaluate to true--Variable specified seq & false otherwise
   not in evaluate to true--if doesn't find a variable specified       sequence and false otherwise.
(9)Identify:-Compare the memory location of two objects.
   is evaluate to True if variable on either side of operator point to some object and false operator.
   is not evaluate to false is variable on either side some object and true other.

Operator Precedence

**           Exponentiation(raise of power)

~ + -      Complement,Unary plus,minus

* / % // multiply divide module floor_division 

+ -          Addition Substraction

>> <<   right and left bitwise shift

&           Bitwise AND

^|          Bitwise exclusive OR, regular OR

<= < > >= Comparison operator

<> == != Equality operator

= %= /= //= -= += *= **= Assignment 

is ,is not Identify operator

in, in not membership/Logical operator 

Decision Making

Decision structure evaluate multiple expression which produce true or false as outcome.

If statement consists of a Boolean expression followed by One or more statement.

If--else statement can be followed by optional else statement which execute when Boolean expression is false.

nested_if statement, you can use if or else if statement inside another if or else if statement.

if(single_statement):-If clause consists only of a single line,it may go on same line as header statement.

#! /usr/bin/python

var=100

if(var==100):print "value of expression is 100"

print "Good Bye"

Loop statement

• In general statement are executed sequentially.
• First statement in function is executed first,followed by second and so on.
• There may be situation, when you need to execute a block of code several number of times.

(1)While_loop:- Repeats a statement or group of statement while is given condition is true. It tests the condition before executing the loop body.

(2)For_loop:- Executes a sequence of statement multiple times that manages the loop variable.

(3)Nested_loop:-You can use one or more loop inside. Only another while,for,or do--- while loop.

while loop:- 

while expression:

    statement(s) 

#prog. for while loop

count=0

while(count<3)

          count=count+1

               print("Hi Mohit")

For_loop

for iteration_var in sequence:

        statement(s)

#prog about for loop

print ("List Itension")

      l=["geeks","for","greeks"]

for i in l:

       print(i)

Using else statement with for loop:-

• We can also combine else statement with for loop like in while loop.
• But as no condition in for loop based on which the execution will terminate.

#Prog with combining else

list=["geeks","for""geeks"]

for index in range (len(list))

          print list[index]

else

          print"Inside else block"

Nested loop:-

for interation_var in sequence:

      for interator_var in sequence:

          statement(s)

          statement(s)

while expression:

      while expression:

              statement(s)

              statement(s)

Loop control statement:-

• Continue
• break
• pass

1. Loop control statement change execution from its normal sequence.
2. When execution leave a scope, all automatic leave a scope, all automatic object that created in scope are destroyed. 

(1)Continue:- Its returns the loop control to the beginning of loop.
        #print all letters except 'e' and 's'
        for letter=='e' or letter=='s':
           continue
              print"Currnet letter:",letter
              var=10
   o/p: g k f o r g k

(2)Break:- Its is bring control out of loop.
         for letter in "geeksforgreeks"
              #Break the loop as soon its seen 'e' or 's'
              if letter=='e' or 'letter=='s':
                 break
              print"Current letter:",letter
    o/p: e
(3)Pass:- We use pass statement to write empty loop, pass is also              used for used for empty control in function and class.
          #An empty loop
          for letter in "greekforgreeks":
          pass
          print "Last letter:",letter

     o/p: s    

• range() – This returns a range object (a type of iterable).
• xrange() – This function returns the generator object that can be used to display numbers only by looping. Only particular range is displayed on demand and hence called “lazy evaluation“