PyThon - Notes

\...NOTES.../

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Day 1 - What is Programming and Python?

1) What is Programming

• Programming is a way for us to tell computers what to do. Computer is a very dumb machine and it only does what we tell it to do.

• Hence, we learn programming and tell computers to do what we are very slow at - computation. If I ask you to calculate 5+6, you will immediately say 11.

How about 23453453 X 56456?

• You will start searching for a calculator or jump to a new tab to calculate the same. These 100 days of code series will help you learn

• python from starting to the end. We will start from 0 and by the time we end this course, I promise you will be a Job ready Python developer!

2) What is Python?

• Python is a dynamically typed, general purpose programming language that supports an object-oriented programming approach as well as a functional programming approach.

• Python is an interpreted and a high-level programming language.

• It was created by Guido Van Rossum in 1989.

3) Features of Python

• Python is simple and easy to understand.

• It is Interpreted and platform-independent which makes debugging very easy.

• Python is an open-source programming language.

• Python provides very big library support. Some of the popular libraries include NumPy, Tensorflow, Selenium, OpenCV, etc.

• It is possible to integrate other programming languages within python.

4) What is Python used for

• Python is used in Data Visualization to create plots and graphical representations.

• Python helps in Data Analytics to analyze and understand raw data for insights and trends.

• It is used in AI and Machine Learning to simulate human behavior and to learn from past data without hard coding.

• It is used to create web applications.

• It can be used to handle databases.

• It is used in business and accounting to perform complex mathematical operations along with quantitative and qualitative analysis.

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Day 3 - Modules and pip in Python!

Module is like a code library which can be used to borrow code written by somebody else in our python program. There are two types of modules in python:

1. Built in Modules - These modules are ready to import and use and ships with the python interpreter. there is no need to install such modules explicitly.

2. External Modules - These modules are imported from a third party file or can be installed using a package manager like pip or conda.

Since this code is written by someone else, we can install different versions of a same module with time.

1) The pip command

• It can be used as a package manager pip to install a python module. Lets install a module called pandas using the following command

pip install pandas

Using a module in Python (Usage)

We use the import syntax to import a module in Python.

Here is an example code:

import pandas

# Read and work with a file named 'words.csv'

df = pandas.read_csv('words.csv')

print(df) # This will display first few rows from the words.csv file

Similarly, we can install other modules and look into their documentations for usage instructions.

We will find ourselves doing this often in the later part of this course.

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Day 4 - Our First Program

• Today we will write our first ever python program from scratch. It will consist of a bunch of print statements.

• print can be used to print something on the console in python

Quick Quiz

Write a program to print a poem in Python.

print("---Your poem here---")

Please make sure you attempt this. Might be easy for some of you but please finish each and every task.

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Day 5 - Comments, Escape sequence & Print in Python

Welcome to Day 5 of 100DaysOfCode. Today we will talk about Comments, Escape Sequences and little bit more about print statement in Python.We will also throw some light on Escape Sequences.

1) Python Comments

• A comment is a part of the coding file that the programmer does not want to execute, rather the programmer uses it to either explain a block of code or to avoid the execution of a specific part of code while testing.

2) Single-Line Comments:

• To write a comment just add a ‘#’ at the start of the line.

Example 1

#This is a 'Single-Line Comment'

print("This is a print statement.")

Output:

This is a print statement.

Example 2

print("Hello World !!!") #Printing Hello World

Output:

Hello World !!!

Example 3:

print("Python Program")

#print("Python Program")

Output:

Python Program

3) Multi-Line Comments:

• To write multi-line comments you can use ‘#’ at each line or you can use the multiline string.

Example 1: The use of ‘#’.

#It will execute a block of code if a specified condition is true.

#If the condition is false then it will execute another block of code.

p = 7

if (p > 5):

print("p is greater than 5.")

else:

print("p is not greater than 5.")

Output:

p is greater than 5.

Example 2: The use of multiline string.

"""This is an if-else statement.

It will execute a block of code if a specified condition is true.

If the condition is false then it will execute another block of code."""

p = 7

if (p > 5):

print("p is greater than 5.")

else:

print("p is not greater than 5.")

Output

p is greater than 5.

4) Escape Sequence Characters

• To insert characters that cannot be directly used in a string, we use an escape sequence character.

• An escape sequence character is a backslash \ followed by the character you want to insert.

• An example of a character that cannot be directly used in a string is a double quote inside a string that is surrounded by double quotes:

print("This doesnt "execute")

print("This will \" execute")

More on Print statement

The syntax of a print statement looks something like this:

print(object(s), sep=separator, end=end, file=file, flush=flush)

Other Parameters of Print Statement

1) object(s): Any object, and as many as you like. Will be converted to string before printed

2) sep='separator': Specify how to separate the objects, if there is more than one. Default is ' '

3) end='end': Specify what to print at the end. Default is '\n' (line feed)

4) file: An object with a write method. Default is sys.stdout

Parameters 2 to 4 are optional

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Day 6 - Variables and Data Types

1) What is a variable?

• Variable is like a container that holds data. Very similar to how our containers in kitchen holds sugar, salt etc.

• Creating a variable is like creating a placeholder in memory and assigning it some value. In Python it’s as easy as writing:

a = 1

b = True

c = "Harry"

d = None

• These are four variables of different data types.

2) What is a Data Type?

• Data type specifies the type of value a variable holds. This is required in programming to do various operations without causing an error.

• In python, we can print the type of any operator using type function:

a = 1

print(type(a))

b = "1"

print(type(b))

• By default, python provides the following built-in data types:

1. Numeric data: int, float, complex

int: 3, -8, 0

float: 7.349, -9.0, 0.0000001

complex: 6 + 2i

2. Text data: str

str: "Hello World!!!", "Python Programming"

3. Boolean data:

Boolean data consists of values True or False.

4. Sequenced data: list, tuple

• list: A list is an ordered collection of data with elements separated by a comma and enclosed within square brackets.

Lists are mutable and can be modified after creation.

Example:

list1 = [8, 2.3, [-4, 5], ["apple", "banana"]]

print(list1)

Output:

[8, 2.3, [-4, 5], ['apple', 'banana']]

• Tuple: A tuple is an ordered collection of data with elements separated by a comma and enclosed within parentheses. Tuples are immutable and cannot be modified after creation.

Example:

tuple1 = (("parrot", "sparrow"), ("Lion", "Tiger"))

print(tuple1)

Output:

(('parrot', 'sparrow'), ('Lion', 'Tiger'))

5. Mapped data: dict

• dict: A dictionary is an unordered collection of data containing a key:value pair.

The key:value pairs are enclosed within curly brackets.

Example:

dict1 = {"name":"Sakshi", "age":20, "canVote":True}

print(dict1)

Output:

{'name': 'Sakshi', 'age': 20, 'canVote': True}

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Day - 7 Operators

• Python has different types of operators for different operations. To create a calculator we require arithmetic operators.

1) Arithmetic operators

Operator Operator Name Example

+ Addition 15+7

- Subtraction 15-7

* Multiplication 5*7

** Exponential 5**3

/ Division 5/3

% Modulus 15%7

// Floor Division 15//7

Exercise

n = 15

m = 7

ans1 = n+m

print("Addition of",n,"and",m,"is", ans1)

ans2 = n-m

print("Subtraction of",n,"and",m,"is", ans2)

ans3 = n*m

print("Multiplication of",n,"and",m,"is", ans3)

ans4 = n/m

print("Division of",n,"and",m,"is", ans4)

ans5 = n%m

print("Modulus of",n,"and",m,"is", ans5)

ans6 = n//m

print("Floor Division of",n,"and",m,"is", ans6)

Explanation

Here 'n' and 'm' are two variables in which the integer value is being stored.

Variables 'ans1' , 'ans2' ,'ans3', 'ans4','ans5' and 'ans6' contains the outputs corresponding to

addition, subtraction, multiplication, division, modulus and floor division respectively.

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Day - 8

Exercise 1 - Create a Calculator

Create a calculator capable of performing addition, subtraction,

multiplication and division operations on two numbers.

Your program should format the output in a readable manner!

print(" Simple Calculator \n")

a = 5

b = 4

print("The Addition of", a, "+", b, "is", a+b)

print("The Subtraction of", a, "-", b, "is", a-b)

print("The Multiplication of", a, "*", b, "is", a*b)

print("The Division of", a, "/", b, "is", a/b)

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Day - 9 - Typecasting in Python

1) Typecasting in python

• The conversion of one data type into the other data type is known as type casting in python or type conversion in python.

• Python supports a wide variety of functions or methods like: int(), float(), str(), ord(), hex(), oct(), tuple(), set(), list(), dict(), etc. for the type casting in python.

2) Two Types of Typecasting:

••Explicit Conversion (Explicit type casting in python)

••Implicit Conversion (Implicit type casting in python).

• Explicit typecasting:

The conversion of one data type into another data type, done via developer or programmer's intervention or manually as per the requirement, is known as explicit type conversion.

It can be achieved with the help of Python’s built-in type conversion functions such as int(), float(), hex(), oct(), str(), etc .

Example of explicit typecasting:

string = "15"

number = 7

string_number = int(string) #throws an error if the string is not a valid integer

sum= number + string_number

print("The Sum of both the numbers is: ", sum)

Output:

The Sum of both the numbers is 22

• Implicit type casting:

Data types in Python do not have the same level i.e. ordering of data types is not the same in Python. Some of the data types have higher-order, and some have lower order.

While performing any operations on variables with different data types in Python, one of the variable's data types will be changed to the higher data type.

According to the level, one data type is converted into other by the Python interpreter itself (automatically). This is called, implicit typecasting in python.

Python converts a smaller data type to a higher data type to prevent data loss.

Example of implicit type casting:

# Python automatically converts

# a to int

a = 7

print(type(a))

# Python automatically converts b to float

b = 3.0

print(type(b))

# Python automatically converts c to float as it is a float addition

c = a + b

print(c)

print(type(c))

Ouput:

10.0

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Day - 10 - Taking User Input in python

• In python, we can take user input directly by using input() function.

• This input function gives a return value as string/character hence we have to pass that into a variable.

Syntax:

variable=input()

• But input function returns the value as string. Hence we have to typecast them whenever required to another datatype.

Example:

variable=int(input())

variable=float(input())

• We can also display a text using input function. This will make input() function take user input and display a message as well

Example:

a=input("Enter the name: ")

print(a)

Output:

Enter the name: Harry

Harry

----------------------------------

print(" Medium Calculator \n")

a = input("Enter Your First Number : ", )

b = input("Enter Your Second Number : ", )

print("\nAnswer Are... \n")

print("The Addition of", a, "+", b, "is", int(a)+int(b))

print("The Subtraction of", a, "-", b, "is", int(a)-int(b))

print("The Multiplication of", a, "*", b, "is", int(a)*int(b))

print("The Division of", a, "/", b, "is", int(a)/int(b))

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Day - 11 - Strings

1) What are strings?

• In python, anything that you enclose between single or double quotation marks is considered a string.

• A string is essentially a sequence or array of textual data. Strings are used when working with Unicode characters.

Example

name = "Harry"

print("Hello, " + name)

Output

Hello, Harry

Note: It does not matter whether you enclose your strings in single or double quotes, the output remains the same.

• Sometimes, the user might need to put quotation marks in between the strings.

Example, consider the sentence: He said, “I want to eat an apple”.

• How will you print this statement in python?: He said, "I want to eat an apple".

We will definitely use single quotes for our convenience

print('He said, "I want to eat an apple".')

2) Multiline Strings

• If our string has multiple lines, we can create them like this:

a = """Lorem ipsum dolor sit amet,

consectetur adipiscing elit,

sed do eiusmod tempor incididunt

ut labore et dolore magna aliqua."""

print(a)

3) Accessing Characters of a String

• In Python, string is like an array of characters. We can access parts of string by using its index which starts from 0.

• Square brackets can be used to access elements of the string.

print(name[0])

print(name[1])

4) Looping through the string

• We can loop through strings using a for loop like this:

for character in name:

print(character)

• Above code prints all the characters in the string name one by one!

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Day - 12 - String Slicing & Operations on String

1) Length of a String

• We can find the length of a string using len() function.

Example:

fruit = "Mango"

len1 = len(fruit)

print("Mango is a", len1, "letter word.")

Output:

Mango is a 5 letter word.

2) String as an array

• A string is essentially a sequence of characters also called an array. Thus we can access the elements of this array.

Example:

pie = "ApplePie"

print(pie[:5])

print(pie[6]) #returns character at specified index

Output:

Apple

Note: This method of specifying the start and end index to specify a part of a string is called slicing.

3) Slicing Example:

pie = "ApplePie"

print(pie[:5]) #Slicing from Start

print(pie[5:]) #Slicing till End

print(pie[2:6]) #Slicing in between

print(pie[-8:]) #Slicing using negative index

Output:

Apple

Pie

pleP

ApplePie

4) Loop through a String:

• Strings are arrays and arrays are iterable. Thus, we can loop through strings.

Example:

alphabets = "ABCDE"

for i in alphabets:

print(i)

Output:

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Day13 - StringMethods

String methods

• Python provides a set of built-in methods that we can use to alter and modify the strings.

1. upper() :

• The upper() method converts a string to upper case.

Example:

str1 = "AbcDEfghIJ"

print(str1.upper())

Output:

ABCDEFGHIJ

2. lower()

• The lower() method converts a string to lower case.

Example:

str1 = "AbcDEfghIJ"

print(str1.lower())

Output:

Abcdefghij

3. strip() :

• The strip() method removes any white spaces before and after the string.

Example:

str2 = " Silver Spoon "

print(str2.strip)

Output:

Silver Spoon

4. rstrip() :

• the rstrip() removes any trailing characters.

Example:

str3 = "Hello !!!"

print(str3.rstrip("!"))

Output:

Hello

5. replace() :

• The replace() method replaces all occurences of a string with another string.

Example:

str2 = "Silver Spoon"

print(str2.replace("Sp", "M"))

Output:

Silver Moon

6. split() :

• The split() method splits the given string at the specified instance and returns the separated strings as list items.

Example:

str2 = "Silver Spoon"

print(str2.split(" ")) #Splits the string at the whitespace " ".

Output:

['Silver', 'Spoon']

• There are various other string methods that we can use to modify our strings.

7. capitalize() :

• the capitalize() method turns only the first character of the string to uppercase and the rest other characters of the

string are turned to lowercase. The string has no effect if the first character is already uppercase.

Example:

str1 = "hello"

capStr1 = str1.capitalize()

print(capStr1)

str2 = "hello WorlD"

capStr2 = str2.capitalize()

print(capStr2)

Output:

Hello

Hello world

8. center() :

• The center() method aligns the string to the center as per the parameters given by the user.

Example:

str1 = "Welcome to the Console!!!"

print(str1.center(50))

Output:

Welcome to the Console!!!

• We can also provide padding character. It will fill the rest of the fill characters provided by the user.

Example:

str1 = "Welcome to the Console!!!"

print(str1.center(50, "."))

Output:

............Welcome to the Console!!!.............

9. count() :

• The count() method returns the number of times the given value has occurred within the given string.

Example:

str2 = "Abracadabra"

countStr = str2.count("a")

print(countStr)

Output:

10. endswith() :

• The endswith() method checks if the string ends with a given value. If yes then return True, else return False.

Example :

str1 = "Welcome to the Console !!!"

print(str1.endswith("!!!"))

Output:

True

• We can even also check for a value in-between the string by providing start and end index positions.

Example:

str1 = "Welcome to the Console !!!"

print(str1.endswith("to", 4, 10))

Output:

True

11. find() :

• The find() method searches for the first occurrence of the given value and returns the index where it is present.

If given value is absent from the string then return -1.

Example:

str1 = "He's name is Dan. He is an honest man."

print(str1.find("is"))

Output:

• As we can see, this method is somewhat similar to the index() method. The major difference being that index() raises

an exception if value is absent whereas find() does not.

Example:

str1 = "He's name is Dan. He is an honest man."

print(str1.find("Daniel"))

Output:

-1

12. index() :

• The index() method searches for the first occurrence of the given value and returns the index where it is present.

If given value is absent from the string then raise an exception.

Example:

str1 = "He's name is Dan. Dan is an honest man."

print(str1.index("Dan"))

Output:

• As we can see, this method is somewhat similar to the find() method. The major difference being that index() raises

an exception if value is absent whereas find() does not.

Example:

str1 = "He's name is Dan. Dan is an honest man."

print(str1.index("Daniel"))

Output:

ValueError: substring not found

13. isalnum() :

• The isalnum() method returns True only if the entire string only consists of A-Z, a-z, 0-9. If any other characters or

punctuations are present, then it returns False.

Example 1:

str1 = "WelcomeToTheConsole"

print(str1.isalnum())

Output:

True

15. isalpha() :

• The isalnum() method returns True only if the entire string only consists of A-Z, a-z. If any other characters or

punctuations or numbers(0-9) are present, then it returns False.

Example :

str1 = "Welcome"

print(str1.isalpha())

Output:

True

16. islower() :

• The islower() method returns True if all the characters in the string are lower case, else it returns False.

Example:

str1 = "hello world"

print(str1.islower())

Output:

True

17. isprintable() :

• The isprintable() method returns True if all the values within the given string are printable, if not, then return False.

Example :

str1 = "We wish you a Merry Christmas"

print(str1.isprintable())

Output:

True

17. isspace() :

• The isspace() method returns True only and only if the string contains white spaces, else returns False.

Example:

str1 = " " #using Spacebar

print(str1.isspace())

str2 = " " #using Tab

print(str2.isspace())

Output:

True

18. istitle() :

• The istitile() returns True only if the first letter of each word of the string is capitalized, else it returns False.

Example:

str1 = "World Health Organization"

print(str1.istitle())

Output:

True

Example:

str2 = "To kill a Mocking bird"

print(str2.istitle())

Output:

False

19. isupper() :

• The isupper() method returns True if all the characters in the string are upper case, else it returns False.

Example :

str1 = "WORLD HEALTH ORGANIZATION"

print(str1.isupper())

Output:

True

20. startswith() :

• The endswith() method checks if the string starts with a given value. If yes then return True, else return False.

Example :

str1 = "Python is a Interpreted Language"

print(str1.startswith("Python"))

Output:

True

21. swapcase() :

• The swapcase() method changes the character casing of the string. Upper case are converted to lower case and lower case to upper case.

Example:

str1 = "Python is a Interpreted Language"

print(str1.swapcase())

Output:

pYTHON IS A iNTERPRETED lANGUAGE

22. title() :

• The title() method capitalizes each letter of the word within the string.

Example:

str1 = "He's name is Dan. Dan is an honest man."

print(str1.title())

Output:

He'S Name Is Dan. Dan Is An Honest Man.

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Day - 14 - If Else Conditionals

1. if-else Statements

• Sometimes the programmer needs to check the evaluation of certain expression(s),

whether the expression(s) evaluate to True or False. If the expression evaluates to False,

then the program execution follows a different path than it would have if the expression had evaluated to True.

• Based on this, the conditional statements are further classified into following types:

if-else

if-else-elif

nested if-else-elif.

• An if……else statement evaluates like this:

if the expression evaluates True:

Execute the block of code inside if statement. After execution return to the code out of the if……else block.\

if the expression evaluates False:

Execute the block of code inside else statement. After execution return to the code out of the if……else block.

Example:

applePrice = 210

budget = 200

if (applePrice <= budget):

print("Alexa, add 1 kg Apples to the cart.")

else:

print("Alexa, do not add Apples to the cart.")

Output:

Alexa, do not add Apples to the cart.

2. elif Statements

• Sometimes, the programmer may want to evaluate more than one condition, this can be done using an elif statement.

• Working of an elif statement

Execute the block of code inside if statement if the initial expression evaluates to True. After execution return to the code out of the if block.

Execute the block of code inside the first elif statement if the expression inside it evaluates True. After execution return to the code out of the if block.

Execute the block of code inside the second elif statement if the expression inside it evaluates True. After execution return to the code out of the if block.

Execute the block of code inside the nth elif statement if the expression inside it evaluates True. After execution return to the code out of the if block.

Execute the block of code inside else statement if none of the expression evaluates to True. After execution return to the code out of the if block.

Example:

num = 0

if (num < 0):

print("Number is negative.")

elif (num == 0):

print("Number is Zero.")

else:

print("Number is positive.")

Output:

Number is Zero.

3. Nested if statements

• We can use if, if-else, elif statements inside other if statements as well.

Example:

num = 18

if (num < 0):

print("Number is negative.")

elif (num > 0):

if (num <= 10):

print("Number is between 1-10")

elif (num > 10 and num <= 20):

print("Number is between 11-20")

else:

print("Number is greater than 20")

else:

print("Number is zero")

Output:

Number is between 11-20

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Day - 15

Exercise 2 - Good Morning Sir

• Create a python program capable of greeting you with Good Morning, Good Afternoon and Good Evening.

• Your program should use time module to get the current hour. Here is a sample program and documentation link for you:

import time

timestamp = time.strftime('%H:%M:%S')

print(timestamp)

timestamp = time.strftime('%H')

print(timestamp)

timestamp = time.strftime('%M')

print(timestamp)

timestamp = time.strftime('%S')

print(timestamp)

# https://docs.python.org/3/library/time.html#time.strftime

-------------

#--Importing Time Module--

import time

#--Using Time Module for time--

time = time.strftime('%H : %M : %S')

#--Checking Conditions for detecting time--

if time >= '06 : 00 : 00' and time <= '10 : 59 : 59':

print("Good Morning Sir")

elif time >= '11 : 00 : 00' and time <= '14 : 59 : 59':

print("Good Noon Sir")

elif time >= '15 : 00 : 00' and time <= '17 : 59 : 59':

print("Good Afternoon Sir")

elif time >= '18 : 00 : 00' and time <= '20 : 59 : 59':

print("Good Evening Sir")

elif time >= '21 : 00 : 00' and time <= '01 : 59 : 59':

print("Good Night Sir")

elif time >= '02 : 00 : 00' and time <= '03 : 59 : 59':

print("It's too early to get up now Sir.")

print("You can sleep again.")

elif time >= '04 : 00 : 00' and time <= '05 : 59 : 59':

print("It's early morning Sir.")

print("If you want, you can sleep again.")

#--Printing the real Time--

print("The time now is = ", time)

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Day - 16 - Match Case

Match Case Statements

• To implement switch-case like characteristics very similar to if-else functionality, we use a match case in python.

If you are coming from a C, C++ or Java like language, you must have heard of switch-case statements. If this is your

first language, dont worry as I will tell you everything you need to know about match case statements in this video!

• A match statement will compare a given variable’s value to different shapes, also referred to as the pattern.

The main idea is to keep on comparing the variable with all the present patterns until it fits into one.

• The match case consists of three main entities :

1) The match keyword

2) One or more case clauses

3) Expression for each case

• The case clause consists of a pattern to be matched to the variable, a condition to be evaluated if the pattern matches,

and a set of statements to be executed if the pattern matches.

• Syntax:

match variable_name:

case ‘pattern1’ : //statement1

case ‘pattern2’ : //statement2

…

case ‘pattern n’ : //statement n

• Example:

x = 4

# x is the variable to match

match x:

# if x is 0

case 0:

print("x is zero")

# case with if-condition

case 4 if x % 2 == 0:

print("x % 2 == 0 and case is 4")

# Empty case with if-condition

case _ if x < 10:

print("x is < 10")

# default case(will only be matched if the above cases were not matched)

# so it is basically just an else:

case _:

print(x)

Output:

x % 2 == 0 and case is 4

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Day - 17 - For Loops

1) Introduction to Loops

• Sometimes a programmer wants to execute a group of statements a certain number of times.

This can be done using loops. Based on this loops are further classified into following main types;

A) for loop

B) while loop

2) The for Loop

• for loops can iterate over a sequence of iterable objects in python. Iterating over a sequence is

nothing but iterating over strings, lists, tuples, sets and dictionaries.

• Example: iterating over a string:

name = 'Abhishek'

for i in name:

print(i, end=", ")

Output:

A, b, h, i, s, h, e, k,

• Example: iterating over a list:

colors = ["Red", "Green", "Blue", "Yellow"]

for x in colors:

print(x)

Output:

Red

Green

Blue

Yellow

• Similarly, we can use loops for lists, sets and dictionaries.

3) range():

• What if we do not want to iterate over a sequence? What if we want to use for loop for a

specific number of times?

• Here, we can use the range() function.

Example:

for k in range(5):

print(k)

Output:

• Here, we can see that the loop starts from 0 by default and increments at each iteration.

• But we can also loop over a specific range.

Example:

for k in range(4,9):

print(k)

Output:

---------------------------------------------------------------

Day18 - While Loops

1) Python while Loop

• As the name suggests, while loops execute statements while the condition is True.

As soon as the condition becomes False, the interpreter comes out of the while loop.

Example:

count = 5

while (count > 0):

print(count)

count = count - 1

Output:

• Here, the count variable is set to 5 which decrements after each iteration. Depending

upon the while loop condition, we need to either increment or decrement the counter

variable (the variable count, in our case) or the loop will continue forever.

2) Else with While Loop

• We can even use the else statement with the while loop. Essentially what the else statement

does is that as soon as the while loop condition becomes False, the interpreter comes out of

the while loop and the else statement is executed.

Example:

x = 5

while (x > 0):

print(x)

x = x - 1

else:

print('counter is 0')

Output:

counter is 0

3) Do-While loop in python

• do..while is a loop in which a set of instructions will execute at least once (irrespective of the condition)

and then the repetition of loop's body will depend on the condition passed at the end of the while loop.

It is also known as an exit-controlled loop.

4) How to emulate do while loop in python?

• To create a do while loop in Python, you need to modify the while loop a bit in order to get similar

behavior to a do while loop.

• The most common technique to emulate a do-while loop in Python is to use an infinite while loop with a break

statement wrapped in an if statement that checks a given condition and breaks the iteration if that condition becomes true:

Example

while True:

number = int(input("Enter a positive number: "))

print(number)

if not number > 0:

break

Output

Enter a positive number: 1

Enter a positive number: 4

Enter a positive number: -1

-1

•••Explanation•••

This loop uses True as its formal condition. This trick turns the loop into an infinite loop.

Before the conditional statement, the loop runs all the required processing and updates the

breaking condition. If this condition evaluates to true, then the break statement breaks out

of the loop, and the program execution continues its normal path.

---------------------------------------------------------------

Day 19 - break and continue

1) break statement

• The break statement enables a program to skip over a part of the code. A break statement

terminates the very loop it lies within.

example

for i in range(1,101,1):

print(i ,end=" ")

if(i==50):

break

else:

print("Mississippi")

print("Thank you")

output

1 Mississippi

2 Mississippi

3 Mississippi

4 Mississippi

5 Mississippi

50 Mississippi

2) Continue Statement

• The continue statement skips the rest of the loop statements and causes the next

iteration to occur.

example

for i in [2,3,4,6,8,0]:

if (i%2!=0):

continue

print(i)

output

---------------------------------------------------------------

Mr_Parth

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