SCHOOL OF COMPUTING
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
UNIT – I – Python Programming – SBS1304
1
, I. OVERVIEW OF PROGRAMMING
A programming language is a formal computer language or constructed language designed to
communicate instructions to a machine, particularly a computer. Programming languages can be used
to create programs to control the behaviour of a machine or to express algorithms.
INTRODUCTION OF PYTHON
Python is an object-oriented, high level language, interpreted, dynamic and multipurpose programming
language.
Python is easy to learn yet powerful and versatile scripting language which makes it attractive for
Application Development.
Python's syntax and dynamic typing with its interpreted nature, make it an ideal language for scripting
and rapid application development in many areas.
Python supports multiple programming pattern, including object oriented programming, imperative
and functional programming or procedural styles.
Python is not intended to work on special area such as web programming. That is why it is known as
multipurpose because it can be used with web, enterprise, 3D CAD etc.
We don't need to use data types to declare variable because it is dynamically typed so we can write
a=10 to declare an integer value in a variable.
Python makes the development and debugging fast because there is no compilation step included in
python development and edit-test-debug cycle is very fast.
It is used for GUI and database programming, client- and server-side web programming, and
application testing.
It is used by scientists writing applications for the world's fastest supercomputers and by children first
learning to program.
HISTORY OF PYTHON
Python was conceptualized by Guido Van Rossum in the late 1980s. Rossum published the first version
of Python code (0.9.0) in February 1991 at the CWI (Centrum Wiskunde & Informatica) in the
Netherlands, Amsterdam. Python is derived from ABC programming language, which is a general-
purpose programming language that had been developed at the CWI. Rossum chose the name "Python",
since he was a big fan of Monty Python's Flying Circus. Python is now maintained by a core
development team at the institute, although Rossum still holds a vital role in directing its progress.
COMPILER vs INTERPRETER
An interpreter is a program that reads and executes code. This includes source code, pre-compiled
code, and scripts. Common interpreters include Perl, Python, and Ruby interpreters, which execute
Perl, Python, and Ruby code respectively.
Interpreters and compilers are similar, since they both recognize and process source code.
However, a compiler does not execute the code like and interpreter does. Instead, a compiler simply
converts the source code into machine code, which can be run directly by the operating system as an
executable program.
Interpreters bypass the compilation process and execute the code directly.
2
,Interpreters are commonly installed on Web servers, which allows developers to run executable scripts
within their webpages. These scripts can be easily edited and saved without the need to recompile the
code. Without an interpreter, the source code serves as a plain text file rather than an executable
program.
PYTHON VERSIONS
Python 1.0
Python 2.0
Python 3.0
PYTHON FEATURES
Easy to learn, easy to read and easy to maintain.
Portable: It can run on various hardware platforms and has the same interface on all
platforms.
Extendable: You can add low-level modules to the Python interpreter.
3
, Scalable: Python provides a good structure and support for large programs. Python has
support for an interactive mode of testing and debugging.
Python has a broad standard library cross-platform.
Everything in Python is an object: variables, functions, even code. Every object has an ID, a
type, and a value.
Python provides interfaces to all major commercial databases.
Python supports functional and structured programming methods as well as OOP.
Python provides very high-level dynamic data types and supports dynamic type checking.
Python supports GUI applications
Python supports automatic garbage collection.
Python can be easily integrated with C, C++, and Java.
APPLICATIONS OF PYTHON
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)
Test frameworks
Multimedia
Scientific computing
Text processing
TYPES OF PROGRAM ERRORS
We distinguish between the following types of errors:
1. Syntax errors: errors due to the fact that the syntax of the language is not respected.
2. Semantic errors: errors due to an improper use of program statements.
3. Logical errors: errors due to the fact that the specification is not respected.
From the point of view of when errors are detected, we distinguish:
1. Compile time errors: syntax errors and static semantic errors indicated by the compiler.
2. Runtime errors: dynamic semantic errors, and logical errors, that cannot be detected by the
compiler (debugging).
Syntax errors
Syntax errors are due to the fact that the syntax of the Java language is not respected.
Let us see some examples of syntax errors.
Example 1: Missing semicolon:
int a = 5 // semicolon is missing
Compiler message:
4
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
UNIT – I – Python Programming – SBS1304
1
, I. OVERVIEW OF PROGRAMMING
A programming language is a formal computer language or constructed language designed to
communicate instructions to a machine, particularly a computer. Programming languages can be used
to create programs to control the behaviour of a machine or to express algorithms.
INTRODUCTION OF PYTHON
Python is an object-oriented, high level language, interpreted, dynamic and multipurpose programming
language.
Python is easy to learn yet powerful and versatile scripting language which makes it attractive for
Application Development.
Python's syntax and dynamic typing with its interpreted nature, make it an ideal language for scripting
and rapid application development in many areas.
Python supports multiple programming pattern, including object oriented programming, imperative
and functional programming or procedural styles.
Python is not intended to work on special area such as web programming. That is why it is known as
multipurpose because it can be used with web, enterprise, 3D CAD etc.
We don't need to use data types to declare variable because it is dynamically typed so we can write
a=10 to declare an integer value in a variable.
Python makes the development and debugging fast because there is no compilation step included in
python development and edit-test-debug cycle is very fast.
It is used for GUI and database programming, client- and server-side web programming, and
application testing.
It is used by scientists writing applications for the world's fastest supercomputers and by children first
learning to program.
HISTORY OF PYTHON
Python was conceptualized by Guido Van Rossum in the late 1980s. Rossum published the first version
of Python code (0.9.0) in February 1991 at the CWI (Centrum Wiskunde & Informatica) in the
Netherlands, Amsterdam. Python is derived from ABC programming language, which is a general-
purpose programming language that had been developed at the CWI. Rossum chose the name "Python",
since he was a big fan of Monty Python's Flying Circus. Python is now maintained by a core
development team at the institute, although Rossum still holds a vital role in directing its progress.
COMPILER vs INTERPRETER
An interpreter is a program that reads and executes code. This includes source code, pre-compiled
code, and scripts. Common interpreters include Perl, Python, and Ruby interpreters, which execute
Perl, Python, and Ruby code respectively.
Interpreters and compilers are similar, since they both recognize and process source code.
However, a compiler does not execute the code like and interpreter does. Instead, a compiler simply
converts the source code into machine code, which can be run directly by the operating system as an
executable program.
Interpreters bypass the compilation process and execute the code directly.
2
,Interpreters are commonly installed on Web servers, which allows developers to run executable scripts
within their webpages. These scripts can be easily edited and saved without the need to recompile the
code. Without an interpreter, the source code serves as a plain text file rather than an executable
program.
PYTHON VERSIONS
Python 1.0
Python 2.0
Python 3.0
PYTHON FEATURES
Easy to learn, easy to read and easy to maintain.
Portable: It can run on various hardware platforms and has the same interface on all
platforms.
Extendable: You can add low-level modules to the Python interpreter.
3
, Scalable: Python provides a good structure and support for large programs. Python has
support for an interactive mode of testing and debugging.
Python has a broad standard library cross-platform.
Everything in Python is an object: variables, functions, even code. Every object has an ID, a
type, and a value.
Python provides interfaces to all major commercial databases.
Python supports functional and structured programming methods as well as OOP.
Python provides very high-level dynamic data types and supports dynamic type checking.
Python supports GUI applications
Python supports automatic garbage collection.
Python can be easily integrated with C, C++, and Java.
APPLICATIONS OF PYTHON
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)
Test frameworks
Multimedia
Scientific computing
Text processing
TYPES OF PROGRAM ERRORS
We distinguish between the following types of errors:
1. Syntax errors: errors due to the fact that the syntax of the language is not respected.
2. Semantic errors: errors due to an improper use of program statements.
3. Logical errors: errors due to the fact that the specification is not respected.
From the point of view of when errors are detected, we distinguish:
1. Compile time errors: syntax errors and static semantic errors indicated by the compiler.
2. Runtime errors: dynamic semantic errors, and logical errors, that cannot be detected by the
compiler (debugging).
Syntax errors
Syntax errors are due to the fact that the syntax of the Java language is not respected.
Let us see some examples of syntax errors.
Example 1: Missing semicolon:
int a = 5 // semicolon is missing
Compiler message:
4
