what is python ??

• python is simple, easy & Portable.

• python is free & open sourse.

• python is high level, interpreted language.

• python was developed by Guido van Rosum.

• python is interpreted language means when we write python code its executed the code line by line thats why we called python is interpreted language.

• print is function to give output statement in python. simply we can tell "print" is output function.

character set of python language :-

1. letter -> A-Z, a-z
2. Digits -> 0 - 9
3. Special character -> -,+,/,* etc..
4. Whitespaces -> Blank Space, Tab, newline

what is variable in python :- a variable is a name given to a memory location in a program or else we can simply say varibale is a container to store some data.

example - name = "shradha" age = 23 salary = 23000.56

variable names - name, age, salary varibale values - "shradha", 23, 23000.56

Rules for Identifires :-

1. identifires - names of the variable
2. identifires can be combination of uppercase and lowercase letter, digits or an underscore(_). ex. - myVariable, variable_1
3. an identifires can not start with digit. so while variable1 is valid but 1variable in not valid.
4. we can not use special character or symbols like !,#,@,% etc...
5. identifires can be of any length.
6. variables name should be small and meaningful like - when we give our age in that case we take the variable as "myAge". myAge -> camel case letter

• 'type' is a operator to show the datatypes name in our varibles like which datatypes we use in our variables.

Data Types :-

• mainly data types of 5 types in python.
• These data types are unmutable or build-in data types.

1. Integer - +ve value , 0 , -ve value
2. String - "hello", "shradha" etc...
3. Float - 3.91, 4.00 , 9.1 etc..
4. Boolean - True , False
5. None - not assign

Comments in python :-

• when we write some code but we dont want to execute it then we give the comment line to that place so that line of code will not executed.
• comments are of 2 type.

1. single line comment - when we give the single line comments. in python we did it on "#". ex.

   single line comment

   this is a comment

2. Multi line comment - when we gibve the multi line comment in python we did it through """-""". ex. """ multi line comments """

Types of Operator :-

• simply we can say operator is a symbol that performs a certain operation between operands. ex. a + b a,b -> operands
  • -> operator
• there are 4 types of operator are present in python

1. arithmetic operator. - (+,-,/,%,*)
2. Relational operator. - (==, != ,> ,<, >=,<=)
3. assignment operator - (=, +=, -=, *=, /=, %=)
4. logical operator - (and, or, not)

Input in Python :-

• Input() statement is used to accept values(use keyword) from users.

Task to do for practice -

1. write a program to input 2 numbers & print their sum
2. Write a program to input side of a square & print its area.
3. write a program to input 2 floating point numbers & print their average.
4. write a program to input 2 int numbers a & b, print True if a is greater then or equal to . if not print false.

Strings :-

• String is datatype that stores a sequence of characters.

str1 = "this is a good day" str2 = 'This is beautiful day' str3 = """this is a bad day"""

• all these strings are real string because in python, it supports all of these syntax like - "", '',""" """

• \n (new line) - when we want to break our line into a new line then we can give the new line symbol in that place so the line get breaked automatically.

Basic Operation of strings :-

1. concatenation -> "hello" + "world" =
2. Length of String -> len(str)

Indexing of string ->

• webbocket -> 012345678(indexing)
• Always indexing start from '0'.

Slicing of string ->

• Accessing parts of a string.
• ending index is not counting.
• syntax - str[starting_index : ending_index]

str = "webbocket" str[0:3] - web str[:3] - web str[3:] - bocket

Functions of string ->

ex- str = "i am a coder."

1. str.endswith("er.") - returns true if string ends with substring
2. str.capitalize() - returns 1st char is capital
3. str.replace(old,new) - replace all occurances of old with new
4. str.find(word) - returns 1st index of 1st occurrence
5. str.count("am") - counts the occurrence of substring in string

Homework :-

1. write a program to input users first name & print its length.
2. write a program to find the occerrence of '$' in a string.

conditional statement :-

• used to handle the condition in your program.
• syntax (if-elif-else)
• elif means else-if

if(condition): statement1 elif(condition): statement2 else: statement(default)

Homework :-

1. write a program to check if a number entered by the user if odd or even.
2. write a program to find the greatest of 3 numbers entered by the userd.
3. write a program to check if a number is a multiple of 7 or not.

Lists in Python :-

• List is a built-in data type that stores set of values.
• it can store elements of different types like integer, float & string etc..
• in list we can make indexing.
• in list we can find length of the list also.
• in list we can also do the slicing activity.

ex- marks = [87, 45, 67, 83, 45] - array and list student = ["hitesh", 85, "bhubaneswar"] - list

List Slicing :-

• it similar to string slicing.
• syntax :- list_name[starting_idx : ending_idx]
• ending index is not included.

marks = [23,25,67,78,98] marks[1:4] -> [25,67,78] marks[:3] -> [23,25,67] marks[2:] -> [67,78,98]

List Methods :-

list = [9,4,7,8,1] list.append(6) - adds one element at the end of the list - [9,4,7,8,1,6] list.sort() - sort the elements in assending order - [1,4,7,8,9] list.sort(reverse=True) - sorts the element in decending order - [9,8,7,4,1] list.reverse() - reversing the list - [1,8,7,4,9] list.insert(idx,el) - insert the element at index list.remove(1) - remove the firt occurrance of element - [9,7,8,1] list.pop(idx) - remove element at index

git :-

• git is a open source repository system where we can save, manipulate, colaborate our code with any one else.
• in our software era, everyone can use git system for their software development.
• we also called git is a version control system.
• git provides some tools to use their functionality and features ex - github, gitlab etc..

Tuple in Python :-

• Tuple is a build in data type that lets us create immutable(the value can't be changeble) sequence of values.
• ex. tup = (87,67,98,34,45)
• tup[0] -> 87
• tup[1] -> 67
• we can do the tuple as

1. tup1 = () -> empty tuple
2. tup2 = (1,) -> tuple
3. tup3 = (34,67,89,20) -> tuple

• tuple has also satisfy the slicing property.

tuple methods:-

• tup.index(element) -> returns index of first occurrence
• tup.count(element) -> returns the count total occurrence

ex. tup = (2,1,3,1,3,3) tup.index(2) -> 3
tup.count(3) -> 3

Homework :-

1. write a program to ask the user to enter names of their 3 favorite movies & store them in a list.
2. write a program if a list contains a palindrome of elements.
3. write a program to count the number of students with the "A" grade in the following tuples. ex. ("c","D","A","A","B","B","A"). store the above value in a list & sort them from "a" to "D".

Dictionary in Python :-

• Dictionary are used to store the data values in key:value pair.
• They are unordered, mutable(changeable) & don't allow duplicate keys.
• ex- dict = { "name" : "shradha", "cgpa" : 9.8, "marks": [98,96,95], }
• the left part of the dictionary are the keys & right side part in their values so dictionary contains key:value pair structure.

Nested Dictionary in python :-

• Dictionary also satisfy the nested property.
• Dictionaru under dictionary is called nested dictionary.
• ex. student = { "name" : "mithun", "score": { "chem" : 98, "math" : 87, "phy" : 79 } }

Dictionary Methods :-

1. myDict.keys() - it returns all keys.
2. myDict.values() - it returna all values
3. myDict.items() - it will returns all key:value pair as tuple.
4. myDict.get("key") - returns the key according to values.
5. myDict.update(newDict) - insert the specified items to the dictionary.

set in python :-

• set is the collection of the unordered items.
• Each element in the set must be unique & immutable(can't change).
• ex. nums = {1,2,3,4,5} set2 = {5,8,9,4}

set method :-

1. set.add(element) -> adds an element
2. set.remove(element) -> remove an element
3. set.clear() -> clear all elements
4. set.pop() -> remove a random value of set
5. set.union(set2) -> combine both set values & returns a new set
6. set.intersection(set2) -> combines the common value & returns a new set.

ex. set1 = {1,2,3,2,4} set2 = {3,7,2,6,4} set1.union(set2) -> {1,2,3,4,6,7} set1.intersection(set2) -> {2,3,4}

Loops in Python:-

• Loops are used to repeat instruction.
• In python there are 2 loops - While loop, For loop

1. while loop:- syntax - intialization while condition: statement increament/decrement.

office-works :-

1. print numbers from 1 to 100
2. print numbers from 100 to 1
3. print the multiplication table of number n.
4. print the elements of the following list using a loop. [1,4,9,16,25,36,49,64,81,100]
5. search for a number x in this tuple using loop (1,4,9,16,25,36,49,64,81,100)

Break & Continue :-

• break: break is used to terminate the loop when encountered.
• continue: terminates execution in the current iteration & continue execution of the loop with the next iteration.

2. For Loop:-

• For loop are used for sequential traversal. for traversing list, string, tuple etc.
• syntax:- for val in list: statement..

Homeworks :- (using for loop)

1. print the element of the following list using a loop: [1,4,9,16,25,36,49,64,81,100]
2. search for a number x in this tuple using loop. (1,4,9,16,25,36,49,64,81,100)

Range() :-

• range function returns a sequence of numbers, starting from 0 by default, and increaments by 1 (by default), and stops before a specified number.

• syntax -> range(start , stop, step)

office-work :- (using for & range)

1. print numbers from 1 to 100
2. print numbers from 100 to 1
3. print the multiplication table of a number n

Functions in Python:-

• Function is a block of statements that performs a specific task.
• syntax :- def func_name(parameter 1, parameter 2..): some statement returns val

func_name(arg1, arg2..) #function call

• Functions are of 2 types in python

1. Built-in function - print(), len(), type(), range() ... etc
2. user defined function - user can develop the function.

office Work :-

1. write a function to print the length of a list(list is the parameter)
2. write a function to print the element of a list in a single line(list is the paraneter)
3. write a function to find the factorial of n (n is the parameter) factorial means - suppose i want to get the factorial of 5, 5! = 5 * 4 * 3 * 2 * 1 syntax of factorial -> n! = 1 * 2 * 3 ... n * (n-1) 4! = 4 * 3 * 2 * 1 3! = 3 * 2 * 1
4. write a function to convert USD to INR.

Recursion in python :-

• when the function calls itself repeatedly is called recursion and this process we called recurance relation.

• ex. print n to 1 backword

  def show(n):
     if(n == 0): #base case, where our program stopped their working
        return
     print(n)
     show(n-1)
  
  show(5)
  
  suppose i take n = 5 then it will print, 5,4,3,2,1
  

Object Oriented programming in Python :-

• To map with real world scenarios, we strated using objects in code. This is called object oriented programming(OOP).

1st concept-> procedural programming 2nd concept-> functional programming 3rd concept-> object orientd programming

Class & Object in python :-

• class is a blueprint for creating objects. ex.-> creating a class class Student: name = "web bocket"

ex.-> creating a object(instance) s1 = Student() print(s1.name) #web bocket

init Function (constructor) :-

• All class have a function called init(), which is always executed when the class is being initiated.

ex. -> creating a class class Student: def init(self, fullname): self.name = fullname

ex. -> creating a object s1 = Student("web bocket") print(s1.name)

Note:- The self parameter is a reference to the current instance of the class, and is used to access variable that belongs to the class.

class & instance Attributes:-

university -> college1, college2, college3 , college4 student1, student2, student3, student4

• colleges and students are the attributes of university.

methods in python :-

• Methods are function that belongs to objects.

ex. -> creating class class Student: def init(self, fullname): self.name = fullname def hello(self): print("hello", self.name)

ex. -> creating object s1 = Student("rohan") s1.hello()

Abstraction:-

• Hiding the implementation details of a class and only showing the essential features to the user.

Encapsulation:-

• Wrapping data and function into a single unit(object).

practice question -

• create Account class with 2 attributes - balance & account no. & create methods for debit, credit & printing the total balance.

Private(like) Attributes & Methods :-

• private attributes & methods are meant to be used only within the class and are not accessible from outside the class.
• the private class attributes are written in __(attributes) so that we call it private attributes of a class.

Inheritance :-

• when one class(child class) derives the properties & methods of another class(parent class).

• syntax :- class car:

class ToyotaCar(car):

• in python inheritance are of 3 types.

1. single inheritance
2. Multi-level inheritance
3. Multiple inheritance

Polymorphism: Operator Overloading:-

• when the same operator is allowed to have different meaning accordingly to the context.
• In that polymorphism we can use Dunder functions.

1. a + b -> add
2. a - b -> sub
3. a * b -> mul
4. a / b -> truediv
5. a % b -> mod

ex - (+) print(1 + 2) #3 (addition) print("web" + "bocket") #web bocket (concatination) print([1,2,3] + [4,5,6]) #[1,2,3,4,5,6] (merged)