Input , output , processing

# input
a = input("Enter a number")

# output
print(a)

• One thing to note here that the default type will be a string from the input() and you may need to type cast it to work as expected for example

a = input("Enter a number")
if a==5:
	print("HI")

• this program will not work as expected (run and find out) (happens because int(5) is not same as str(5))

a = int(input("Enter a number"))
if a==5:
	print("HI")

Data types

Operators

1. Arithmetic

Arithmetic Operators

a , b  = 1 , 2 
a + b  # 3 "#" is the single line comment
a - b  # -1  
a * b  # 2 
a / b  # .5 
a % b  #  1 
b ** 2 # 4
a // b # 0

Comparison Operator

a, b = 5, 10

# Equal to
a == b  # False

# Not equal to
a != b  # True

# Greater than
a > b   # False

# Less than
a < b   # True

# Greater than or equal to
a >= b  # False

# Less than or equal to
a <= b  # True

Logical Operators

x, y = True, False

# AND - True if both operands are True
x and y  # False

# OR - True if at least one operand is True
x or y   # True

# NOT - Inverts the Boolean value 0 -> 1 , 1 -> 0
not x    # False
not y    # True

Membership Operators

lst = [1, 2, 3, 4]
name = "Arun"

# IN - True if value is found in sequence
2 in lst       # True
"run" in name  # True
5 in lst       # False

# NOT IN - True if value is not found in sequence
5 not in lst   # True
"y" not in name # True

Identity Operators

m = [1, 2]
n = [1, 2]
p = m

# IS - True if both variables point to same object
m is p    # True

m is n    # False (same values but different objects)

# IS NOT - True if variables point to different objects
m is not n  # True

print(m is n) # False , different objects even if values are sae
print(m == n) # True same value even if different objects

Bitwise Operators

a , b = 1, 2  # 01 , 10

''' Bitwise AND 
  01
& 10 '''
a & b  # 0

#Bitwise OR
# 11 
a | b  # 3

# Bitwise XOR
 
a ^ b  # 3

# Bitwise NOT
# this might be confusing explain later.
~a     # -2

#  Left Shift (<<)

a << 1  # 2

#Right Shift (>>)
a >> 1  # 0

• explain biwise not 🏁 delete

Assignment Operators

x = 10

x += 3  # x = x + 3 → 13
x -= 2  # 11
x *= 2  #  22
x /= 4  # 5.5
x %= 3  #  2.5
x **= 2 #   6.25
x //= 2 #  3.0

Functions

Important things to keep in mind

• intend the defenition of a function from its decleration
• scope is limited within intendations

#syntax

def function_name(parameters):
	.
	.
	.
	return

#example

def sum(a, b):
    return a + b
def differece(a, b):
    return a - b
def division(a, b):
    return a / b
def multiplication(a, b):
    return a * b
print("Sum = ", sum(10, 20))
print("Difference  = ", differece(10, 20))
print("Division = ", division(10, 20))
print("Multiplication = ", multiplication(10, 20))

# find out given number is prime or not
staus = 0
def prime_or_not(number):
    if number % 2 == 0:
        print("Number is not prime")
    else:
        for i in range(2, number // 2):
            status = 1
        if status == 1:
            print("Number is prime")


number = int(input("Enter a number"))
prime_or_not(number)

Control Statements

1. Selection Strucure if else
2. Iteration structure for i in ..

if condition:
  code
else

# Find Largest among 2 numbers
def is_large(num_1,num_2):
    if (num_1 > num_2):
        return True
    else:
        return False
num_1 = int(input("Enter the first Number"))
num_2 = int(input("Enter the second Number"))
print("The Bigger Number is ", is_large(num_1,num_2) and num_1 or is_large(num_2,num_1) and num_2)

# Even or off

for <variable> in range(<an integer expression>):
	code

for i in range(4):
	print(i)

# print from 1 to 10
for i in range(1,11):
    print(i)

while <condition>:
	<code>

i=1
while (i<11):
    print("2 times " , i , "= " , i*2)
    i+=1

i = 1
while(i<21):
	print(i)
	i+=2

16-08-2024

• Armstron or Not

# check whether armstron or not
# armstrong = sum of cubes of a given number is = the number itself
def armstrong(number):
    sum = 0
    while number != 0:
        a = number % 10
        sum = sum + (a**3)
        number = number // 10
    return sum


number = int(input("Enter a number"))
if number == armstrong(number):
    print("Number is armstrong")
else:
    print("Number is not armstrong")

• armstrong from 1 to 1000

# print armstrong from 1 to 1000
# armstrong = sum of cubes of a given number is = the number itself
def armstrong(number):
    sum = 0
    while number != 0:
        a = number % 10
        sum = sum + (a**3)
        number = number // 10
    return sum


for i in range(1, 1000):
    if i == armstrong(i):
        print(i)

3. Find if prime

# find out given number is prime or not
staus = 0
def prime_or_not(number):
    if number % 2 == 0:
        print("Number is not prime")
    else:
        for i in range(2, number // 2):
            status = 1
        if status == 1:
            print("Number is prime")


number = int(input("Enter a number"))
prime_or_not(number)

Strings

1. .center()

s ='Hello'
print(s.center(30))

# print ** before and after
print(s.center(30, "*"))

2. Is alpha

   Returns True is all letters are Alphabets

# return true if it is alpha
print(s.isalpha())

# Output
# True

3. .isdigit()

   Return True only if the string contains all digits

# Return false
print(s.isdigit())

s = 5
print(str(s).isdigit())

3. .count()

s = "Hi hi hi hi "
print(s.count("i"))
print(s.count("hi"))
# output
# 4
# 3

4. .endswith()

Returns true if string ends with the provided character

print(s.endswith("hi")) # Returns true if string ends with the provided character

5. str.find()

   Returns the starting location of the given subsequence

print(s.find("Hi"))
# output
# 0

6. .join()

   Contatinates 2 strings

a = "Hello "
b = "Sir"
c = [a, b]
print(" ".join(c))
print("*".join(c))
# output
# Hello Sir
# Hello *Sir

7. .lower()

a = "HELLo"
print(a.lower())
# output
# hello

• In and Not in operator

2024-09-03

Lists

first = [1, 2, 3, 4]
  second = list(range(1, 5))
  print(first)
  print(" length is ", len(first))
  # print single

 for i in range(0, len(first)):
     print(first[i])

2024-09-12

Dictionary

#syntax

a_dict = {"key" : "value" , "key1" : "value1" }
a_dict["key"]
a_dict["key2"]

#example

a = { "name" : "Something" , "age" : "23"}
print(a['name'])
print(a["age"])

• Adding Keys and replacing keys
• We can use [] operator

a_dict["some key"] = "new_value"

#example

a = { "age" : "23","name" : "Something" }
print(a['name'])
print(a["age"])
a["college"] = "GCEK"
print(a)

• Replacing Values

a["college"] = "GCEK"
print(a)
a["college"] = "CET"
print(a)

Set

• uses only elements seperated by ","
  #example

fruits = {"fruit_1","fruit_2","fruit_3"}

a = { "age" : "23","name" : "Something" }
print(a['name'])
print(a["age"])
a["college"] = "GCEK"
print(a)
a["college"] = "CET"
print(a)
# Prints None if the value is not exist
print(a.get("marks",None)) # .get is the replacement for has_key
print(a.get("marks",True))
print(a.get("marks",False))
print(a.get("name",False))
##### Alternative to get
try:
	print(a["marks"])
except:
	 print(None)

# .pop method is used to remove
a.pop("name")
print(a)
a.pop("name",None)

# len(a) return the length of entries
print(len(a))

############## SET ###########
fruits = {'apple','orenge'}

print("apple" in fruits)
print(fruits)
## pop in set
# It remove the last index item
fruits.pop()
print(fruits)

2024-09-27

Key: Class , Objects , OOP , Polymorphism

class Person:
  def __init__(self,fname,lname):
    # __init__ is a constructor it runs automatically when a object is created.
    self.firstname = fname
    self.lastname = lname

  # Functions are __init__ and printname()
  # firstname and lastname are the variables inside the function
  def printname(self):
    print(self.firstname,self.lastname)

  def printlength(self):
      print(len(self.firstname), len(self.lastname))

  def get_age(self, age1, age2):
      self.age1 = age1
      self.age2 = age2

  def print_age(self):
      print(f"John Age is {self.age1} Doe age is {self.age2}")


# How to create Object
x = Person("John","Doe")
# Here x is the object and when the object is created the __init__ is execited
# self is the reference of x
x.printname()

x.get_age(22, 22)
x.print_age()

2024-10-03

Child Class

# class new_child_class(parent_class):
class Student(Person):
  pass

• super().init ->

"""Create a Person Class and create child class named Student and add graduation year for Parent class and create a clid class ??? """


class Person:
    def __init__(self, fname, lname):
        self.firstname = fname
        self.lastname = lname

    def printname(self):
        print(self.firstname, self.lastname)


Nivin = Person("Nivin", "Ravichandran")
# Nivin.printname()


class Student(Person):
    def __init__(self, fname, lname, year):
        super().__init__(fname, lname)
        self.graduationyear = year

    def printname(self):
	    print(self.firstname,self.lastname,self.graduationyear)


Nivin_New = Student("Nivin", "Ravichandran", 2022)

# Nivin_New.printname()

print(Nivin_New.lastname)


class New_Gen_Z(Student):
    def __init__(self, fname, lname, year, age):
        super().__init__(fname, lname, year)
        self.age = age

    def printname(self):
        print(self.firstname, self.lastname, self.graduationyear, self.age)


Manual_New = New_Gen_Z("Manu", "Old", 2022, 22)

Manual_New.printname()

Types of Inheritance

• Mainly 4 types of Inheritance

1. Single Inheritance

graph TB
A --> B
C --> B

2. Multiple Inheritance

graph TB
A --> B
A --> C
A --> D

3. Hybrid Inheritance

graph TB
A --> B
A --> C
C --> D
C--> E

Questions

"""Create a class Student with atributes name and roll no. and a method dataprint() for displauing the same. Create two instance of the class and call the method for each instance of the class"""


class Student:
    def __init__(self, name, rollno):
        self.name = name
        self.roll_number = rollno

    def dataprint(self):
        print(f"Name  : {self.name} Roll No : {self.roll_number}")


n = Student("neh", 35)
meg = Student("meg", 32)

n.dataprint()
meg.dataprint()

2024-10-05

PolyMorphism

behave differently based on the type of data they are handling

• Function Overloading: Same name but performs different operations

class Shape:
    def area(self):
        pass

class Rectangle(Shape):
    def __init__(self, length, width):
        self.length = length
        self.width = width

    def area(self):
        return self.length * self.width

class Circle(Shape):
    def __init__(self, radius):
        self.radius = radius

    def area(self):
        return 3.14 * self.radius ** 2

R1 = Rectangle(1,2) 
C1 = Circle(2)
print(f"Area of rectangle:  {R1.area()}")
print(f"Area of Circle : {C1.area()}")

• Operator Overloading: Same operator does diffrent things

int(a) + int(b) = int # addition
str(a) + str(a) = str # Contcatination

print(5 + 5 ) # addition 
print("Hello" + " World!") # Concatination

Abstract Class

if a class contains abstract method then it is called as abstract class

from abc import ABC, abstractmethod
class Shape:
	@abstractmethod
    def area(self):
        pass
class Circle(Shape):
	def area(self):
		return 3.14 * self.radius ** 2 

from abc import ABC, abstractmethod
class Shape:
	@abstractmethod
	def area(self):
		pass
class Circle(Shape):
	def __init__(self,radius):
		self.radius = radius
	def area(self):
		return 3.14 * self.radius ** 2 
C1 = Circle(2)
print(f"Area is  {C1.area()}")

from abc import ABC, abstractmethod
class Shape:
	@abstractmethod
	def area(self):
		pass
class Circle(Shape):
	def __init__(self,radius):
		self.radius = radius
	def sqr_area(self):
		return (3.14 * self.radius ** 2) ** 2
C1 = Circle(2)
print(f"Area is ", {C1.sqr_area()})

Some source says that this programm will not work because we havent yet defined area() which is a abstract method but this exceutes just fine #doYourOwnReasearch

Exception

• [[#Type error Exception]]
• [[#Name error Exception]]
• [[#Exception Handling]]

Type error Exception

Type error occurs when the type of the variable is not correct

Name error Exception

Name error occurs when the variable is not defined

Exception Handling

#example

try:
    <Statement>
except <exception type>:
    <Statement>

#anotherExample

try:
    something

except Exception as e:
    print(f"Error {e}")

Multiple Exception Handling

except (TypeError,ValueError,RuntimError) :

Q: Calculate integer error?