Introduction to Python

 

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1. What is software?

Software is a set of instructions for the hardware.

2. What is Python and what are its applications?

Python is an object-oriented programming language that is easy to learn and simple to implement.

Applications of Python

Python is a versatile language that has applications in almost every field

• Artificial intelligence (AI)
• Machine Learning (ML)
• Big Data
• Smart Devices/Internet of Things (IoT)
• Cyber Security
• Game Development
• Backend Development, etc.

3. What are the features of Python?

Features of Python:

• Easy to learn & code
• Open Source Programming Language
• Object-Oriented Language
• Dynamic Typed Language
• Large Standard Library

4. Is Python case-sensitive?

Yes, Python is case-sensitive. The username, UserName, and userName are three different variables, and using these names interchangeably causes an error.

Code

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username = "Rahul"

print(username)

print(userName)

PYTHON

Output

Rahul

NameError: name 'userName' is not defined

5. Is Python a dynamically typed programming language?

Yes, Python is a dynamically typed language. This means that in Python the type checking of a variable is done only as code runs, and the type of a variable is allowed to change over its lifetime. There is no need to declare the type of the variable

While programming languages like C, Java, C++, etc are statically typed languages where we cannot change the data type of a variable during the execution of the program.

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x = 6

print(type(x))

x = 'Rahul'

print(type(x))

PYTHON

Output

<class 'int'>

<class 'str'>

6. What are the advantages of Python over Java?

Basis of Comparison	Python	Java
Learning curve	Easy to learn	Compared to Python, it's difficult to learn
Typing	Dynamically-typed	Statically-typed
Syntax	Easy to read and remember	Difficult to read and remember
Applications	Artificial Intelligence, Data Science and Machine Learning applications	Enterprise, Embedded and Cross-platform applications
Code Length	Fewer lines of code compared to Java	More lines of code compared to Python
Example Program	print("Hello World")	public class Simple { public static void main(String args[]){ System.out.println("Hello World"); }}

7. How to perform the arithmetic operations using Python?

Addition

The addition is denoted by

+

sign. It gives the sum of two numbers.

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print(2 + 5)

print(1 + 1.5)

PYTHON

Output

7

2.5

Subtraction

The subtraction is denoted by

-

sign. It gives the difference between the two numbers.

Code

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print(5 - 2)

PYTHON

Output

3

Multiplication

The multiplication is denoted by

*

sign.

Code

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print(2 * 5)

print(5 * 0.5)

PYTHON

Output

10

2.5

Division

The division is denoted by

/

sign.

Code

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print(5 / 2)

print(4 / 2)

PYTHON

Output

2.5

2.0

Modulus

To find the remainder between two numbers, we use the Modulus operator

%

Code

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print(6 % 3)

PYTHON

Output

0

Exponent

To calculate a power b, we use Exponent Operator

**

Code

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print(2 ** 3)

PYTHON

Output

8

8. What is floor division?

To find integral part of quotient we use Floor Division Operator

//

.

• a // b

  Code

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print(3 // 2)

PYTHON

Output

1

9. What is Operator Precedence in Python?

The operator precedence determines which operator is executed first if there is more than one operator in an expression.

The operator precedence in Python is listed in the following table. It is in descending order (the upper group has higher precedence than the lower ones).

Operators	Meaning
()	Parentheses
**	Exponent
+x ,  -x ,  ~x	Unary plus, Unary minus, Bitwise NOT
*,   /,   //,   %	Multiplication, Division, Floor division, Modulus
+ ,  -	Addition, Subtraction
<<,   >>	Bitwise shift operators
&	Bitwise AND
^	Bitwise XOR
|	Bitwise OR
==,   !=,   >,   >=,   <,   <=,   is ,  is not ,  in ,  not in	Comparisons, Identity, Membership operators
not	Logical NOT
and	Logical AND
or	Logical OR

BODMAS The standard order of evaluating an expression - Brackets (B) - Orders (O) - Division (D) - Multiplication (M) - Addition (A) - Subtraction (S)

Expression:

(5 * 2) + (3 * 4 + 4 / 2)

Step by Step Explanation

(5 * 2) + (3 * 4 + 4 / 2)

(10) + (3 * 4 + 2)

(10) + (12 + 2)

(10) + (14)

24

Code

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print((5 * 2) + (3 * 4 + 4 / 2))

PYTHON

Output

24

10. What is a Variable?

Variables are like containers for storing values.

Assigning Value to Variable

The following is the syntax for assigning an integer value

10

to a variable

age

1

age = 10

PYTHON

Here the equals to

=

sign is called an Assignment Operator as it is used to assign values to variables.

11. What are Data Types?

In programming languages, every value or data has an associated type to it known as data type. Some commonly used data types

• String
• Integer
• Float
• Boolean

This data type determines how the value or data can be used in the program. For example, mathematical operations can be done on Integer and Float types of data.

12. What are the numeric data types in Python?

The Numeric Data Types in Python are:

• Integers
• Float
• Complex Numbers

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a = 10

print("Type of a: ", type(a))

b = 10.0

print("Type of b: ", type(b))

c = 10 + 20j

print("Type of c: ", type(c))

PYTHON

Output

Type of a: <class 'int'>

Type of b: <class 'float'>

Type of c: <class 'complex'>

13. What is meant by mutability? Name some mutable data types?

Mutable means capable of being changed. In Python, objects whose value can be changed are said to be mutable.

Some of the mutable data types in Python are list, dictionary, set and user-defined classes.

14. What is meant by immutability? Name some immutable data types?

Immutable means capable of not being changed. In Python, objects whose value cannot be changed are said to be immutable.

Some of the immutable data types in Python are tuple, integer, boolean, string, etc.

15. What is type conversion or type casting?

Converting the value of one data type to another data type is called Type Conversion or Type Casting. We can convert

• String to Integer
• Integer to Float
• Float to String and so on.

String to Integer

int()

converts valid data of any type into integer

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a = "5"

a = int(a)

print(type(a))

print(a)

PYTHON

Output

<class 'int'>

5

Integer to String

str()

converts data of any type into a string.

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a = input()

a = int(a)

b = input()

b = int(b)

result = a + b

print("Sum: " + str(result))

PYTHON

Input

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3

Output

Sum: 5

Similarly,

• float()
   -> Converts to a float data type
• bool()
   -> Converts to a boolean data type

16. What is a String?

A String is a stream of characters enclosed within quotes. Stream of Characters

• Capital Letters ( A – Z )
• Small Letters ( a – z )
• Digits ( 0 – 9 )
• Special Characters (~ ! @ # $ % ^ . ?,)
• Space

Some examples:

• "Hello, World!"
• "some@example.com"
• "1234"

17. What is String Slicing?

Obtaining a part of a string is called String Slicing.

Syntax:

variable_name[start_index:end_index]

• end_index
   is not included in the slice.

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message = "Hi Ravi"

part = message[3:7]

print(part)

PYTHON

Output

Ravi

Slicing to End

If the end index is not specified, slicing stops at the end of the string.

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message = "Hi Ravi"

part = message[3:]

print(part)

PYTHON

Output

Ravi

Slicing from Start

If the start index is not specified, slicing starts from the index 0.

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message = "Hi Ravi"

part = message[:2]

print(part)

PYTHON

Output

Hi

Extended Slicing

Syntax:

variable[start_index:end_index:step]

Step determines the increment between each index for slicing.

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a = "Waterfall"

part = a[1:8:2]

print(part)

PYTHON

Output

aefl

18. How to reverse a string?

A string can be reversed using extended slicing.

Syntax:

variable[start:end:negative_step]

-1

for step will reverse the order of the characters.

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string_1 = "Program"

string_2 = string_1[::-1]

print(string_2)

PYTHON

Output

margorP

19. What is string 

capitalize()

 in Python?

The

capitalize()

method converts the first character of a string to an uppercase letter and all other alphabets to lowercase.

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sentence = "proGraMmiNg"

capitalized_string = sentence.capitalize()

print(capitalized_string)

PYTHON

Output

Programming

20. What is string 

replace()

 in Python?

The

replace()

returns a new string after replacing all the occurrences of the old substring with the new substring.

Syntax:

str_var.replace(old, new)

Code

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sentence = "teh cat and teh dog"

sentence = sentence.replace("teh", "the")

print(sentence)

PYTHON

Output

the cat and the dog

21. What is 

round()

 function?

Rounds the float value to the given number of decimal digits.

Syntax:

round(number, digits(optional))

digits

-> defines the number of decimal digits to be considered for rounding.

• When 
  digits
   not specified, the default value is 0.

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a = round(3.14159, 2)

print(a)

a = round(5.6777)

print(a)

PYTHON

Output

3.14

6

22. How to write comments in Python?

A comment starts with a hash

#

It can be written in its own line next to a statement of code.

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n = 5

# Finding if Even

even = (n % 2 == 0)

print(even) # prints boolean value

PYTHON

Output

False