Review Python

• What is Program
• What is Programming Language
• Features of Python Language
• Installing python on your Computer
• Working mode of Python
• Variable
• Data Type in Python
• Type() Function
• Input() Function
• Operator in Python
• Precedence of Operators
• Comment in Python
• Types of Control Structures
• Conditional Statement

We all know that how computer works. It divided into
three part:-
A computer perform all these operations with the help of
program.
“A Program is a step-by-step sequence of instructions ”
that help the computer to perform the given task.
There are many programming language that you can use
to write a programs.
For Example:- C,C++, Python, Java, etc.
Input Process Output

“A programming language is a set of commands,
instructions, and other syntax use to create a
software program”
Types of Programming Language:-
Like Add, Sub, Mul

Python is a general purpose, high level
programming language.
It was created by Guido van Rossum at CWI (Centrum Wiskunde &
Informatica), and released in 1991 which is:
• Simple and interactive
• Platform independent
• Case sensitive
• Object oriented
• Interpreted language
• Use variable without declaration
It can be use for designing Console app(Where text base application is
involved like C and C++ language), Desktop app, Web application,
Mobile application, Machine learning, Robotics and perform scientific
computing.
Some popular applications which are designed using Python are:
You Tube, Google, Instagram, Quora.

You can download it for free from the following
website: www.python.org/download
After installing Python, you will get the following screen:-

Python work on two different modes:-
Modes of Python
Interactive
Mode
Script
Mode

• In the interactive mode of Python, the
interpreter executes the statement one by
one. After the first statement is executed
successfully, it move to the next statement.
How to work on Interactive Mode:-
• Click on the Start button > All program
> Python 3.7 > IDLE (Python3.7)
• It will open the Python Shell Window
where you will see the python prompt
(>>>)

Type the following command in interactive mode
and see the output:-
Interactive Mode

If you need to write long piece of
Python code then we use Script Mode.
How to write code in script mode:-
• Click on the File > New File option
or Ctrl+N
• A new file opens, write the program
and save your file by selecting the
File > Save option OR Ctrl+S
• The files in Python are saved with
the extension .py
• Once your file is saved, you can open
the same file by selecting the File >
Open option and executed the file
using F5
OR
Click on Run > Run Module
Option Output
Program

The print() function
used in the
interactive mode as
well as in the Script
mode. It is used to
display user define
messages on the
screen. Using print()
function, we can also
show the result of an
expression, once it is
processed.

We can use many separator with print() to format the
displayed result. These include:-
‘,’ (Comma):- To print the next value after a space.
‘n’ (Newline):- To print the new value in the next line.
‘t’ (Tab):- To print the next value after a tab space
(1 tab = 5 space)

• IDLE is an Integrated
Development Environment
for editing and running Python
commands. If we type an
arithmetic expression at the
python prompt and press the
Enter key, the interpreter
automatically evaluates it and
displays the result. In this
case, interpreter acts as a
calculator.
• In this mode, if you are
evaluating an expression, it is
not necessary to use the print()
function.

Smallest individual element of a program is called as
Token. Everything you see inside a program is a token.
Types Of Token
1. keywords(Reserve words)
2. Identifiers (Names that the programmer defines)
3. Literals(Constants)
4. Operators(Special Symbols that operate on data and
produce results)
5. Delimiters (Grouping, punctuation, and
assignment/binding symbols)

• Variables are containers for
storing data values.
• A variable can store one value
at a time.
• You can use variables
without declare their type.
e.g:-
A=10 (Value 10 store in
variable a)

When we specify the variable name, we need to follow
certain rules:
• A variable name must start with an alphabet(Capital or
Small) or an Underscore(_).
• A variable name consist of alphabets, digits, and
underscore. No other character is allowed.
• A keyword cannot be used as a variable name
• Space is not allowed in a variable name.
Note-
• A variable name can be of any range.
• Variable name are case sensitive (e.g.- stud_name and
Stud_name are different variable)

• Data types are the classification or categorization of data items.
• Data types represent a kind of value which determines what
operations can be performed on that data.
The main data type used in Python are :
Data type
Int
Used when you have
to work on whole
numbers (+ive or -ive)
e.g.- 100, 50
Plain Integer
-2147483648
to
+2147483647
Long Integer
>2147483647
Float
Represent
float point
value.
e.g 12.45356
String
Collection of
characters
enclosed with
single or
double quotes
e.g.- ‘Python’
Bool
Represent
logical
value in
the form
of True
and False
e.g.- 10>5

• If You want to know what type of data you are working
with, you use type() function.
• It is used to return the data type of a value.
Syntax:- Type(Object)
e.g. :-

• Input function is used to take the input from user during the
execution of program as required.
Syntax:- Input(prompt)
OR
Syntax:- Datatype(Input(prompt))
Prompt is a String, representing a default message before the input.
e.g:-
a=input(“Enter Your Name”)

Operator is a symbol that performs an operation on one
or more operands.
e.g.-
Python provides different type of operators to work.
They are:-
• Arithmetic Operator (+, -, *, %, /, //,**)
• String operator (+, *)
• Assignment operator (=)
• Relational Operator (<, >, <=,>=,!=, ==)
• Logical Operator (and, or, not)
Operators
Operands
Expression
C=A+B

Arithmetic
Operator
Used to
perform
Arithmetic
operations on
data.
Unary Operator
Work on single
Operand
Unary + and Unary –
e.g.:- a=10,a=-10
Binary Operator
Work on Two
Operand
Addition(+), Subtraction(-),
Multiply(*),
Division(/):-To divide the
number and give the result in
decimal form.
e.g.- 10/4=2.5
Integer Division(//):- To divide
the no. and give result in
integer form.
e.g.:- 10//4=2
Modulus(%):- To divide the no.
and give remainder
e.g:- 10%3=1
Exponential(**):- To find the
power of the numbers.
e,.g:- 3**4=81
Ternary Operator
Work on Three Operand
also called a conditional
expression.
Or conditional operator

String Operators
Work on string values
Concatenation(+)
Used to join two string values.
e.g. :- ‘Hello’+’World’=HelloWorld
Replication(*)
Used to repeat a string for a
number of time.
e.g. :-
‘Hello’*4=HelloHelloHelloHello

Assignment Operator is used to assign a value.
e.g.:- a=10
The value 10 is assign to variable a.

Relational operators are used to show relationship
between two operands. They compare the values
assigned to the operands and give the output in Boolean
expression.
Relational operators are:-
• Less than ( < )
• Greater than ( > )
• Less than and equal to ( <= )
• Greater than equal to ( >= )
• Not equal to ( != )
• Equal to ( = )

Logical operator are used to
combine two or more conditional
statements. They provide the result
in the form of True and False.
Logical operator has three types:-
and, or, not
and:- Give result ‘True’ if all the
specified condition is true.
or :- Give result ‘True’ if any one
of the specified condition is true.
not:- It reverse or negates the
given condition. If the condition is
True, It evaluate the false and vice
versa.

Operator precedence determines which operator is performed
first in an expression.
If two operators with the same precedence are the part of an
expression, then associativity is taken into consideration.
The associativity of an operator determines the direction of operators
from which side (Either Left to Right or Vice Versa) the expression
should be resolved.
Use BODMAS (Brackets Off Divide Multiply Addition
Subtraction) to evaluate the operators in expression.

Comment are the statements that are added to a
program with the purpose of making the code easier
to understand.
Compiler and interpreters generally ignored
comment during the execution of program.
Types of Comment:-
Types of
Comment
Single Line
Comment
Multiline
Comment

Single Line comment are created by beginning a line with the
hash(#) character and are automatically terminated at the end of
line.
If you want to explain thing in more detail, which is more than one
line such comment are called multiline comment.
Note:- read
green

Statement are generally executed in a sequential
manner. If we want to change the flow of
execution of program by repeating or skipping
the execution of few statement then we use
control statements.
There are three type of control statement:-

In sequential statements, the statements in a program
are executed in a sequential manner, where one
statements are followed by other.
To find the Simple Interest First enter Principle, then
Rate, and then Time. After that it calculate the Simple
Interest.

Conditional statements are also called
decision-making statements. We use
those statements while we want to execute
a block of code when the given condition
is true or false.
There are the following Conditional
(Decision-Making) statement:-
• If statements
• If-else statements
• If-Elif-else statements

Iteration statements or loop statements allow us to
execute a block of statements as long as the condition is true.
When the given condition became false, the control comes out
of the loop and repetition stops.
Iteration statements or loop statements are used when we
need to run same code again and again, each time with a
different value.
In Python Iteration (Loops) statements are of three type :-
1. While Loop
2. For Loop
3. Nested For Loops

Conditional statement check the condition and
execute the statement accordingly. It is a part of
control structure which is use to change the order of
execution of code.
Eg.- Suppose, you want to withdraw some money from
bank ATM. You will allowed to withdraw the money only
if you enter the correct PIN.
Let us analyse it with the help of flow chart
Condition Plan of Action
If correct Pin is entered You can withdraw the money
If incorrect PIN is entered You can not withdraw the money

Flowchart:- Flow chart is a pictorial represent of
your program.

This statement is used when you want to evaluate only
one condition. If the given condition if true then it
perform the course of action other wise it skip the
statement.
Syntax:-
If <condition> :
Statement set
True condition output False condition output

It work with two blocks :- if and else. In case the
conditional expression evaluate true, the statement of
if block is executed and if the result is false, then the
statement in the else block are executed.
Syntax:- if<condition>:
statements set 1
else:
statements set 2
If block is executed else block is executed

If you want to work on multiple conditions in this case
we use if…elif…else statement.
Syntax:-
if<condition>:
statements set 1
elif<condition>:
statement set 2
else:
statement set 3
Program If block executed
elif block executed else block executed

We can also check multiple condition in the
following manner:-
Syntax:-
If<condition>:
statement set 1
elif<condition>:
statement set 2
elif<condition>:
statement set 3
elif<condition>:
statement set 4
else:
statement set 5

Data Type
Two
Control Statement
Comments
F5
F
F
T
T
T

Interactive mode is used when an user wants to run one single line or one block of
code. It runs very quickly and gives the output instantly.
Script Mode is used when the user is working with more than one single code or a
block of code.
✔
Two feature of python that make it user friendly are :-
1. Platform independent
2. Use variable without declaration
The purpose of adding comment in program is making the code easier to
understand.
For single line comment we use # and for multiline comment we use three time
double inverted comma like ( ""“ comment ""“ ) .

If statement:- This statement is used when you want to evaluate only one condition. If
the given condition is true then it perform the course of action otherwise it skip
the statement.
If…else statement:- It work with two blocks :- if and else. In case the conditional
expression evaluate true, the statement of if block is executed and if the result is
false, then the statement in the else block are executed.
When we use + operator with integer it gives the sum of the integer value
whereas if we use + operator with string value it is join two string value.
e.g. :- 10+20=30 +operator with integer value
‘Hello’+’World’ = HelloWorld +operator with string value
a=10, in this statement the value 10 is assign to variable a.
a==10, in this statement the we check whether a is equal to 10 or not

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