Module 1 Review of Python Basics An Introduction

OBJECT ORIENTED
PROGRAMMING
Lec: CSIT362 / CSIT362A
Lab: CSIT361L / CSIT361A-L
Prof. Percival A. Fernandez

ADVANCED PYTHON
PROGRAMMING
Lec: CSDS042
Lab: CSDS041L

• Python is a popular programming language. It was created by Guido van Rossum, and
released in 1991.
• It is used for:
• web development (server-side),
• software development,
• mathematics,
• system scripting.
What is Python

• Python is a high-level, general-purpose and a very popular programming language.
Python programming language (latest Python 3) is being used in web development,
Machine Learning applications, along with all cutting edge technology in Software
Industry.
• Python Programming Language is very well suited for Beginners, also for experienced
programmers with other programming languages like C++ and Java.
What is Python

• Python is a very popular general-purpose interpreted, interactive, object-oriented, and
high-level programming language.
• Python is dynamically-typed and garbage-collected programming language. It was
created by Guido van Rossum during 1985- 1990. Python is a popular programming
language.
What is Python

• If you know Python nicely, then you have a great career ahead. Here are just a few of
the career options where Python is a key skill:
▪ Game developer
▪ Web designer
▪ Python developer
▪ Full-stack developer
▪ Machine learning engineer
▪ Data scientist
Careers with Python
▪Data analyst
▪Data engineer
▪DevOps engineer
▪Software engineer
▪Many more other roles

• Python is currently the most widely used multi-purpose, high-level programming
language.
• Python allows programming in Object-Oriented and Procedural paradigms.
• Python programs generally are smaller than other programming languages like Java.
Programmers have to type relatively less and indentation requirement of the
language, makes them readable all the time.
• Python language is being used by almost all tech-giant companies like – Google,
Amazon, Facebook, Instagram, Dropbox, Uber… etc.
Facts about Python

• The biggest strength of Python is huge collection of standard library which can be
used for the following:
• Machine Learning
• GUI Applications (like Kivy, Tkinter, PyQt etc. )
• Web frameworks like Django (used by YouTube, Instagram, Dropbox)
• Image processing (like OpenCV, Pillow)
• Web scraping (like Scrapy, BeautifulSoup, Selenium)
Facts about Python

• The biggest strength of Python is huge collection of standard library which can be
used for the following – cont.:
• Test frameworks
• Multimedia
• Scientific computing
• Text processing and many more..
Facts about Python

• Python is consistently rated as one of the world's most popular programming
languages.
• Python is fairly easy to learn, so if you are starting to learn any programming language
then Python could be your great choice.
• Today various Schools, Colleges and Universities are teaching Python as their primary
programming language.
Why to learn Python

• There are many other good reasons which makes Python as the top choice of any
programmer:
▪ Python is Open Source which means its available free of cost.
▪ Python is simple and so easy to learn
▪ Python is versatile and can be used to create many different things.
▪ Python has powerful development libraries include AI, ML etc.
▪ Python is much in demand and ensures high salary
Why to learn Python

• Python is a MUST for students and working professionals to become a great Software
Engineer specially when they are working in Web Development Domain.
▪ Python is Interpreted − Python is processed at runtime by the interpreter. You do
not need to compile your program before executing it. This is similar to PERL and
PHP.
▪ Python is Interactive − You can actually sit at a Python prompt and interact with
the interpreter directly to write your programs.
Why to learn Python

▪ Python is Object-Oriented − Python supports Object-Oriented style or technique
of programming that encapsulates code within objects.
▪ Python is a Beginner's Language − Python is a great language for the beginner-
level programmers and supports the development of a wide range of applications
from simple text processing to WWW browsers to games.
Why to learn Python

• Following are important characteristics of Python Programming −
▪ It supports functional and structured programming methods as well as OOP.
▪ It can be used as a scripting language or can be compiled to byte-code for building
large applications.
▪ It provides very high-level dynamic data types and supports dynamic type
checking.
▪ It supports automatic garbage collection.
▪ It can be easily integrated with C, C++, COM, ActiveX, CORBA, and Java.
Characteristics of Python

• The latest release of Python is 3.x. As mentioned before, Python is one of the most
widely used language over the web. I'm going to list few of them here:
• Easy-to-learn − Python has few keywords, simple structure, and a clearly defined
syntax. This allows the student to pick up the language quickly.
• Easy-to-read − Python code is more clearly defined and visible to the eyes.
• Easy-to-maintain − Python's source code is fairly easy-to-maintain.
• A broad standard library − Python's bulk of the library is very portable and cross-
platform compatible on UNIX, Windows, and Macintosh.
Reasons Python

• Interactive Mode − Python has support for an interactive mode which allows
interactive testing and debugging of snippets of code.
• Portable − Python can run on a wide variety of hardware platforms and has the
same interface on all platforms.
• Extendable − You can add low-level modules to the Python interpreter. These modules
enable programmers to add to or customize their tools to be more efficient.
Reasons to use Python

• Databases − Python provides interfaces to all major commercial databases.
• GUI Programming − Python supports GUI applications that can be created and
ported to many system calls, libraries and windows systems, such as Windows
MFC, Macintosh, and the X Window system of Unix.
• Scalable − Python provides a better structure and support for large programs than
shell scripting.
Reasons to use Python

• Python was designed for readability, and has some similarities to the English
language with influence from mathematics.
• Python uses new lines to complete a command, as opposed to other programming
languages which often use semicolons or parentheses.
• Python relies on indentation, using whitespace, to define scope; such as the scope of
loops, functions and classes. Other programming languages often use curly-brackets
for this purpose.
Python Syntax compared to other programming languages

• The Python syntax defines a set of rules that are used to create Python statements
while writing a Python Program.
• The Python Programming Language Syntax has many similarities to Perl, C, and Java
Programming Languages. However, there are some definite differences between the
languages.
• Python syntax can be executed by writing directly in the Command Line:
Python - Basic Syntax

• Or by creating a python file on the server, using the .py file extension, and running it in
the Command Line:
Python - Basic Syntax

• Indentation refers to the spaces at the beginning of a code line.
• Where in other programming languages the indentation in code is for readability only,
the indentation in Python is very important.
• Python uses indentation to indicate a block of code.
• The number of spaces is up to you as a programmer, the most common use is four, but
it has to be at least one.
Python Indentation

❖Python - Interactive Mode Programming
• We can invoke a Python interpreter from command line by typing python at the
command prompt as following −
• Here >>> denotes a Python Command Prompt where you can type your
commands. Let's type the following text at the Python prompt and press the Enter
−
Example Python Program

❖Python - Script Mode Programming
▪ We can invoke the Python interpreter with a script parameter which begins the
execution of the script and continues until the script is finished. When the script is
finished, the interpreter is no longer active.
▪ Let us write a simple Python program in a script which is simple text file. Python
files have extension .py. Type the following source code in a test.py file −
• We assume that you have Python interpreter path set in PATH variable. Now, let's
try to run this program as follows −
Example Python Program

• Comments can be used to explain Python code.
• Comments can be used to make the code more readable.
• Comments can be used to prevent execution when testing code.
• Creating a Comment
• Comments starts with a #, and Python will ignore them:
• Comments can be placed at the end of a line, and Python will ignore the rest of the
line:
Python Comments

• A Python identifier is a name used to identify a variable, function, class, module or
other object. An identifier starts with a letter A to Z or a to z or an underscore (_)
followed by zero or more letters, underscores and digits (0 to 9).
• Python does not allow punctuation characters such as @, $, and % within identifiers.
• Variables are containers for storing data values.
• Creating Variables
• Python has no command for declaring a variable.
• A variable is created the moment you first assign a value to it.
Python Identifiers

• Casting
• If you want to specify the data type of a variable, this can be done with
casting.
Python Identifiers

• Single or Double Quotes?
• String variables can be declared either by using single or double quotes:
• Case-Sensitive
• Variable names are case-sensitive.
#A will not overwrite a
Python Identifiers

• Python programming provides no braces to indicate blocks of code for class and
function definitions or flow control. Blocks of code are denoted by line indentation,
which is rigidly enforced.
• The number of spaces in the indentation is variable, but all statements within the
block must be indented the same amount. For example −
• However, the following block generates an error −
Thus, in Python all the continuous lines indented with same
number of spaces would form a block.
Python Lines and Indentation

• Python Data Types are used to define the type of a variable. It defines what type of
data we are going to store in a variable. The data stored in memory can be of many
types.
• For example, a person's age is stored as a numeric value and his or her address is
stored as alphanumeric characters.
Python Data Types

Python Data Types

• Python numeric data types store numeric values. Number objects are created when
you assign a value to them. For example −
• Python supports four different numerical types −
• int (signed integers)
• long (long integers, they can also be
represented in octal and hexadecimal)
• float (floating point real values)
• complex (complex numbers)
Python Numeric Data Type

• Python Strings are identified as a contiguous set of characters represented in the
quotation marks. Python allows for either pairs of single or double quotes.
• Subsets of strings can be taken using the slice operator ([ ] and [:] ) with indexes
starting at 0 in the beginning of the string and working their way from -1 at the end.
• The plus (+) sign is the string concatenation operator and the asterisk (*) is the
repetition operator in Python. For example −
Python String Data Type

• Operators are used to perform operations on variables and values.
• Python divides the operators in the following groups:
• Arithmetic operators
• Assignment operators
• Comparison operators
• Logical operators
• Identity operators
Python Operators
• Membership operators
• Bitwise operators

• Python arithmetic operators are used to perform
mathematical operations on numerical values. These
operations are Addition, Subtraction, Multiplication,
Division, Modulus, Exponents and Floor Division.
This produce the following
result −
Python Arithmetic Operators

• Python comparison operators compare the values on either
sides of them and decide the relation among them. They are
also called relational operators. These operators are equal,
not equal, greater than, less than, greater than or equal to
and less than or equal to.
This produce the following result −
Python Comparison Operators

• Python assignment operators are used to assign values to
variables. These operators include simple assignment
operator, addition assign, subtraction assign, multiplication
assign, division and assign operators etc.
This produce the following result −
Python Assignment Operators

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