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Python Fundamentals 

These are following the five fundamentals required to master Python: 

1. Datatypes
2. Flow Control
3. Functions
4. File Handling
5. Object & Class 

Figure: Python Programming Language- Fundamentals

1. Datatypes 

All data values in Python are represented by objects and each object or value has a datatype. 

Figure: Python Programming Language – Datatype Features 

There are eight native datatypes in Python Programing Language. 

1. Boolean 
2. Numbers 
3. Strings
4. Bytes & Byte Arrays
5. Lists 
6. Tuples 
7. Sets
8. Dictionaries

The following image will give a description for the same.

 Figure: Python Programming Language – Native Datatypes 

2. Flow Control

Flow Control helps us to understand the execution flow of our program. Let us take a Real–world example to understand this transformation. For this you need to control the execution of your Python program statements using Flow Controls. 

Figure: Python Programming Language- Flow Control

There are six basic flow controls used in Python programming: 

1. If 
2. For 
3. While 
4. Break  
5. Continue 
6. Pass 

If Statement 

The Python compound statement ’if’ lets you conditionally execute blocks of statements. 

Syntax of If statement: 

if expression:
statement (s)
elif expression:
statement (s)
elif expression:
…
else:
statement (s)

                          Figure: Python Programming Language – If – Facebook Login Example 

The above image explains the use of ‘if’ statement using an example of Facebook ID  login. 

1.Facebook login page will direct you to two pages based on whether your username and password is a match to your Facebook account. 

2.If the Facebook password entered is wrong, it will direct you to the page on the left. 

3.If the Facebook password entered is correct, you will be directed to your homepage. 

Let us now look at how Facebook would use the If statement. 

password = facebook_hash(input_password)
if password == hash_password
print (‘Login successful.’)
Else
print (‘Login failed. Incorrect password.’)

The above code just gives a high-level implementation of If statement in the Facebook ID login example used. Facebook hash () function takes the input password as a parameter and compares it with the hash value stored for that user

For Statement 

The for statement supports repeated execution of a statement or block of statements that is controlled by an integrable expression. 

Syntax of For statement: 

for target in integrable:
statement (s)

Figure: Python Programming Language- For – Facebook Friends Example

The ‘for’ statement can be understood from the above example. 

• Listing ‘Friends’ from your profile will display the names and photos of all of your friends 
• To achieve this, Facebook gets your ‘friend list’ list containing all the profiles of your friends 
• Facebook then starts displaying the HTML of all the profiles till the list index reaches ‘NULL’ 
• The action of populating all the profiles onto your page is controlled by ‘for’ statement 

Let us now look at a sample program in Python to demonstrate the For statement 

travelling = input(“Are you travelling? Yes or No:”)
while travelling == ‘yes’:
num = int(input(“Enter the number of people travelling:”))
for num in range(1,num+1):
name = input(“Enter Details \n Name:”)
age = input(“Age:”)
sex = input(“Male or Female:”)
print(“Details Stored \n”,name)
print(age)
print(sex)
print(“Thank you!”)
travelling = input(“Are you travelling? Yes or No:”)
print(“Please come back again.”)

The output is as below: 

Are you travelling?
Yes or No: Yes
Enter the number of people travelling:1
Enter Details
Name: Harry
Age:20
Male or Female: Male
Details Stored
Harry
20
Male
Thank you
Are you travelling? Yes or No: No
Please come back again.

While Statement 

The while statement in Python programming Language supports repeated execution of a statement or block of statements that is controlled by a conditional expression. 

Syntax of While statement: 

while expression:
statement (s)

Figure: Python Programming Language – While – Facebook Newsfeed Example 

We will use the above Facebook Newsfeed to understand the use of while loop.  

• When we login to our homepage on Facebook ID, we have about 10 stories loaded on our newsfeed 
• As soon as we reach the end of the page, Facebook loads another 10 stories onto our newsfeed 

• This demonstrates how ‘while’ loop can be used to achieve this 

Let us now look at a sample program in Python to demonstrate the While statement. 

count = 0
print(‘Printing numbers from 0 to 9’)
while (count<10):
print(‘The count is ‘,count)
count = count+1
print(‘Good Bye’)

This program prints numbers from 0 to 9 using the while statement to restrict the loop till it reaches 9. The output is as below: 

The count is 0
The count is 1
The count is 2
The count is 3
The count is 4
The count is 5
The count is 6
The count is 7
The count is 8
The count is 9

Break Statement 

The break statement is allowed only inside a loop body. When break executes, the loop terminates. If a loop is nested inside other loops, break terminates only the innermost nested loop. 

Syntax of Break statement: 

while True:
x = get_next()
y = preprocess(x)
if not keep_looking(x, y): break
process(x, y)

Figure: Python Programming Language- Break – Alarm and Incoming Call 

The ‘break’ flow control statement can be understanding from the above example. 

• Let us consider the case of an alarm on a mobile ringing at a time. 

• Suppose the phone gets an incoming call in that time the alarm is ringing; the alarm is stopped immediately, and the phone ringer starts ringing. 
• This is how break essentially works. 

Let us now look at a sample program in Python Programing language 

 to demonstrate the Break statement. 

for letter in ‘The Quick Brown Fox. Jumps, Over The Lazy Dog’:
if letter == ‘.’:
break
print (‘Current Letter :’, letter)

This program prints all the letters in a given string. It breaks whenever it encounters a ‘.’ or a full stop. We have done this by using Break statement. The output is as below. 

• Current Letter: T
• Current Letter: h 
• Current Letter:  e 
• Current Letter :  
• Current Letter: Q 
• Current Letter: u
• Current Letter: I
• Current Letter: c 
• Current Letter: k 
• Current Letter :  
• Current Letter: B 
• Current Letter: r
• Current Letter: o 
• Current Letter: w 
• Current Letter: n 
• Current Letter: 
• Current Letter: F 
• Current Letter: o 
• Current Letter: x