Computer Science
Class -XI
Code No. 083
2023-24




CLASS-XI
SUBJECT: COMPUTER SCIENCE (083) – PYTHON
INDEX
NO. CHAPTER NAME 
1 INTRODUCTION TO PYTHON 
 




CHAPTER-1
INTRODUTION TO PYTHON
1.1 Introduction:
 General-purpose Object Oriented Programming language.
 High-level language
 Developed in late 1980 by Guido van Rossum at National 
Research Institute for
Mathematics and Computer Science in the Netherlands.
 It is derived from programming languages such as ABC, 
Modula 3, small talk, Algol-
.
 It is Open Source Scripting language.
 It is Case-sensitive language (Difference between 
uppercase and lowercase letters).
 One of the official languages at Google.
1 Characteristics of Python:
 Interpreted: Python source code is compiled to byte
code as a .pyc file, and this byte
code can be interpreted by the interpreter.
 Interactive
 Object Oriented Programming Language
 Easy & Simple
 Portable
 Scalable: Provides improved structure for supporting 
large programs.
 Integrated
 Expressive Language
1. Python Interpreter:
Names of some Python interpreters are:
 PyCharm
 Python IDLE
 The Python Bundle
 pyGUI
 Sublime Text etc.
There are two modes to use the python interpreter:
i. Interactive Mode
ii. Script Mode

i. Interactive Mode: Without passing python script file 
to the interpreter, directly
execute code to Python (Command line).
Example:
>>>6+3
Output: 9
Fig: Interactive Mode
Note: >>> is a command the python interpreter uses to 
indicate that it is ready. The
interactive mode is better when a programmer deals 
with small pieces of code.
To run a python file on command line:
exec(open(“C:\Python33\python programs\program1.py”).
read( ))
ii. Script Mode: In this mode source code is stored 
in a file with the .py extension
and use the interpreter to execute the contents of 
the file. To execute the script by the
interpreter, you have to tell the interpreter the 
name of the file.
Example:
if you have a file name Demo.py , to run the script 
you have to follow the following
steps:
Step-1: Open the text editor i.e. Notepad
Step-2: Write the python code and save the file 
with .py file extension. (Default
directory is C:\Python33/Demo.py)
Step-3: Open IDLE ( Python GUI) python shell
Step-4: Click on file menu and select the open option
Step-5: Select the existing python file
Step-6: Now a window of python file will be opened
Step-7: Click on Run menu and the option Run Module.

Step-8: Output will be displayed on python shell window.