Revision-of-thehki-basics-of-python.pptx

Computer Science
Class XII ( As per CBSE
Board)
New
syllabus
2020-21
Chapter 1
Revision of the
Basics of Python

Introduction
It is widely used general purpose,high level
programming language.Developed by Guido van Rossum
in 1991.
It is used for:
software development,
web development (server-side),
system scripting,
Mathematics.
Visit School Website for Regular Updates

Features of
Python
1. Easy to use – Due to simple syntax rule
2. Interpreted language – Code execution
& interpretation line by line
3. Cross-platform language – It can run
on windows,linux,macinetosh etc.
equally
4. Expressive language – Less code to be written as
it itself express the purpose of the code.
5. Completeness – Support wide rage of library
6. Free & Open Source – Can be downloaded
freely and source code can be modify for
improvement

Shortcomings of
Python
1. Lesser libraries – as compared to other
programming languages like c++,java,.net
2. Slow language – as it is interpreted
languages,it executes the program slowly.
3. Weak on Type-binding – It not pin point on use of
a single variable for different data type.

How to work in
Python
(i) in Interactive mode
* Search the python.exe file in the drive in which it
is installed.
If found double click it to start python in interactive
mode

How to work in Python
* Click start button -> All programs ->
python<version>->IDLE(Python GUI)

Python command
prompt >>>
Type the following at prompt
print “hello”
print 8*3
print 3**3
k=3+4*3
print k

(ii) in Script mode
Step 1 (Create program file)
Below steps are for simple hello world program
a. Click Start button->All Programs ->
Python<version>->IDLE
b.Now click File->New in IDLE Python Shell
Now type
print “hello”
print “world”
print “python is”,”object oriented programming
lang.”
c. Click File->Save and then save the file

How to work in
Python
(ii) in Script mode
Step 2 (Run program
file)
a. Click Open command from IDLE’s File menu and select
the file you have already saved
b. Click Run-> Run Module
c. It will execute all the commands of program file
and display output in separate python shell
window
Note :- Python comes in 2 flavours – python 2.x and python 3.x . Later one is
Backward incompatible language as decide by Python Software foundation(PSF).
Mean code written in 2.x will not execute on 3.x . Visit the below link for
difference between 2.x & 3.x
https://www.geeksforgeeks.org/important-differences-between-python-2-x-and-
python-3-x-with-examples/

Data
Handling
Most of the computer programming
language support data type, variables,operator and
expression like fundamentals.Python also support these.
Data Types
Data Type specifies which type of value a variable
can store. type() function is used to determine a
variable's type in Python.

Data type
continue
Data Types In Python
1. Number
2. String
3. Boolean
4. List
5. Tuple
6. Set
7. Dictionary

Data type continue
1. Number In Python
It is used to store numeric values
Python has three numeric types:
1. Integers
2. Floating point numbers
3. Complex numbers.

Data type continue
1. Integers
Integers or int are positive or
negative numbers with no decimal point. Integers
in Python 3 are of unlimited size.
e.g.
a= 100
b= -100
c
= 1*20
print(a)
print(b)
print(c)
Output :
- 100
-
100 Visit School Website for Regular Updates

Data type
continue
Type Conversion of Integer
int() function converts any data type to
integer. e.g.
a = "101" # string
b=int(a) # converts string data type to integer.
c=int(122.4) # converts float data type to
integer. print(b)
print(c)Run Code
Output :-
101
122

Data type
continue
2. Floating point numbers
It is a positive or negative real numbers with
a decimal point.
e.g.
a = 101.2
b = -101.4
c = 111.23
d = 2.3*3
p
rint(a)
print(b)
print(c)
p
rint(d)R
un
Code
O
utput :-

Data type
continue
Type Conversion of Floating point numbers
float() function converts any data type to floating
point number.
e.g.
a='301.4' #string
b=float(a) #converts string data type to floating point number.
c=float(121) #converts integer data type to floating point
number. print(b)
print(c)Run Code
Output :
- 301.4
121.0

Data type
continue
3. Complex numbers
Complex numbers are combination of a
real and imaginary part.Complex numbers are in the
form of X+Yj, where X is a real part and Y is imaginary
part. e.g.
a = complex(5) # convert 5 to a real part val and zero imaginary part
print(a)
b=complex(101,23) #convert 101 with real part and 23 as imaginary
part
print(b)Run Code
O
utput :-
(5+0j)

Data type
continue
2. String In Python
A string is a sequence of characters. In python we can create string
using
single (' ') or double quotes (" ").Both are same in python. e.g.
str='computer science'
print('str-', str) # print
string
print('str[0]-', str[0]) # print
first char 'h'
print('str[1:3]-', str[1:3]) # print string from postion 1 to 3 'ell'
print('str[3:]-', str[3:]) # print string staring from 3rd char 'llo
world' print('str *2-', str *2 ) # print string two times
print("str +'yes'-",
Output
str- computer science
str[0]- c
str[1:3]- om
str[3:]- puter science
str +'yes') # concatenated
string
str *2- computer sciencecomputer science
str +'yes'- computer scienceyes

Data type
continue
Iterating through
string
e.g.
str='comp sc'
for i in str:
print(i)
Out
put c
o
m
p
s

Data type
continue
3. Boolean In Python
It is used to store two possible values either true or
false
e.g.
str="comp sc"
boo=str.isupper() # test if string contains upper
case print(boo)
Output
False

Data type continue
4.List In Python
List are collections of items and each item has its own index value.
5. Tuple In Python
List and tuple, both are same except ,a list is mutable python objects and tuple
is immutable Python objects. Immutable Python objects mean you cannot modify
the contents of a tuple once it is assigned.
e.g. of list
list =[6,9]
list[0]=55
print(list[0])
print(list[1])
OUTPUT
55
9
e.g. of
tuple
tup=(66,99)
Tup[0]=3 #
error
message
will be
displayed
print(tup[0]
)

Data type
continue
6. Set In Python
It is an unordered collection of unique and
immutable (which cannot be modified)items.
e.g.
set1={11,22,33,22
}
print(set1)
Output
{33, 11, 22}

Data type
continue
7. Dictionary In Python
It is an unordered collection of items and each
item consist of a key and a value.
e.g.
dict = {'Subject': 'comp sc', 'class': '11'}
print(dict)
print ("Subject : ", dict['Subject'])
print ("class : ", dict.get('class'))
Output
{'Subject': 'comp sc', 'class': '11'}
Subject : comp
sc class : 11

Operator
Operators are special symbols in Python that carry out arithmetic or logical
computation. The value that the operator operates on is called the
operand. Arithmetic operators
Used for mathematical operation
Operator Meaning Example
+ Add two operands or unary plus x + y
+2
- Subtract right operand from the left or unary minus x - y
-2
* Multiply two operands x * y
/ Divide left operand by the right one (always results into float) x / y
% Modulus - remainder of the division of left operand by the right x % y (remainder of x/y)
// Floor division - division that results into whole
number adjusted to the left in the number line
x // y
** Exponent - left operand raised to the power of right x**y (x to the power y)

Operator continue
Arithmatic operator
continue e.g.
x = 5
y = 4
print('x + y =',x+y)
print('x - y =',x-y)
print('x * y =',x*y)
print('x / y =',x/y)
print('x // y =',x//y)
print('x ** y
=',x**y) OUTPUT
('x + y =', 9)
('x - y =', 1)
('x * y =', 20)
('x / y =', 1)
('x // y =', 1)
('x ** y =', 625)
• Write a program in python to calculate the
simple interest based on entered amount ,rate
and time

Operator
continue
Arithmatic operator continue
# EMI Calculator program in
Python def emi_calculator(p, r, t):
r = r / (12 * 100) # one month
interest
t = t * 12 # one month period
emi = (p * r * pow(1 + r, t)) / (pow(1 + r, t) -
1) return emi
# driver code
principal = 10000;
rate = 10;
time = 2;
emi = emi_calculator(principal, rate,
time); print("Monthly EMI is= ", emi)

Operator
continue
Arithmatic operator continue
How to calculate GST
GST ( Goods and Services Tax ) which is included in netprice of
product for get GST % first need to calculate GST Amount by subtract
original cost from Netprice and then apply
GST % formula = (GST_Amount*100) / original_cost
# Python3 Program to compute GST from original and net
prices. def Calculate_GST(org_cost, N_price):
# return value after calculate GST%
return (((N_price - org_cost) * 100) / org_cost);
# Driver program to test above
functions org_cost = 100
N_price = 120
print("GST =
",end='')
print(round(Calculate
_GST(org_cost,
N_price)),end='')

Operator continue
Comparison operators -used to compare
values
> Greater that - True if left operand is greater than the right x > y
< Less that - True if left operand is less than the right x < y
== Equal to - True if both operands are equal x == y
!= Not equal to - True if operands are not equal x != y
>= Greater than or equal to - True if left operand is greater than or equal
to the right
x >= y
<= Less than or equal to - True if left operand is less than or equal to the right x <= y

Operator
continue
Comparison operators
continue
e.g.
x = 101
y = 121
print('x > y is',x>y)
print('x < y is',x<y)
print('x == y is',x==y)
print('x != y is',x!=y)
print('x >= y is',x>=y)
print('x <= y is',x<=y)
Output
('x > y is', False)
('x < y is', True)
('x == y is', False)
('x != y is', True)
('x >= y is', False)
('x <= y is', True) Visit School Website for Regular Updates

Operator
continue
Logical
operators
e.g.
x = True
y =
False
print('x and y is',x and
y) print('x or y is',x or y)
print('not x is',not x)
Outpur
('x and y is',
False) ('x or y is',
True)
('not x is', False)
and True if both the operands are true x and y
or True if either of the operands is true x or y
not True if operand is false (complements the operand) not x

Operator
continue
Bitwise
operators
Used to manipulate bit values.
& Bitwise AND x& y
| Bitwise OR x | y
~ Bitwise NOT ~x
^ Bitwise XOR x ^ y
>> Bitwise right shift x>> 2
<< Bitwise left shift x<< 2

Operator
continue
Bitwise operators
continue
a = 6
b = 3
print ('a=',a,':',bin(a),'b=',b,':',bin(b))
c = 0
c = a & b;
print ("result of AND is ", c,':',bin(c))
c = a | b;
print ("result of OR is ", c,':',bin(c))
c = a ^ b;
print ("result of EXOR is ",
c,':',bin(c)) c = ~a;
print ("result of COMPLEMENT is ",
c,':',bin(c))
c = a << 2;
print ("result of LEFT SHIFT is ", c,':',bin(c))
c = a >> 2;
print ("result of RIGHT SHIFT is ",
Output
('a=', 6, ':', '0b110', 'b=', 3, ':', '0b11')
('result of AND is ', 2, ':', '0b10')
('result of OR is ', 7, ':', '0b111')
('result of EXOR is ', 5, ':', '0b101')
('result of COMPLEMENT is ', -7, ':', '-
0b111') ('result of LEFT SHIFT is ', 24, ':',
'0b11000')
('result of RIGHT SHIFT is ', 1, ':', '0b1')

Operator continue
Python Membership Operators
Test for membership in a sequence
e.g.
a = 5
b = 10
list = [1, 2, 3, 4, 5 ]
if ( a in list ):
print ("Line 1 - a is available in the given list")
else:
print ("Line 1 - a is not available in the given list")
if ( b not in list ):
print ("Line 2 - b is not available in the given list")
else:
print ("Line 2 - b is available in the given list")
output
Line 1 - a is available in the given list
Line 2 - b is not available in the given
list
Operator Description
in Evaluates to true if it finds a variable in the specified sequence and false otherwise.
not in Evaluates to true if it does not finds a variable in the specified sequence and false otherwise.

Operator
continue
Python Identity Operators
e.g.
a = 10
b = 10
print ('Line 1','a=',a,':',id(a), 'b=',b,':',id(b))
if ( a is b ):
print ("Line 2 - a and b have same identity")
else:
print ("Line 2 - a and b do not have same identity")
OUTPUT
('Line 1', 'a=', 10, ':', 20839436, 'b=', 10, ':',
20839436)
Line 2 - a and b have same identity
Operat
or
Description
is Evaluates to true if the variables on either side of the operator point to the same
object and false otherwise.
is not Evaluates to false if the variables on either side of the operator point to the same
object and true otherwise.

Operator
continue
Operators Precedence :highest precedence to lowest precedence
table
Operator Description
** Exponentiation (raise to the power)
~ + - Complement, unary plus and minus (method names for the last two are +@ and -@)
* / % // Multiply, divide, modulo and floor division
+ - Addition and subtraction
>> << Right and left bitwise shift
& Bitwise 'AND'td>
^ | Bitwise exclusive `OR' and regular `OR'
<= < > >= Comparison operators
<> == != Equality operators
= %= /= //= -= +=
*= **=
Assignment operators
is is not Identity operators
in not in Membership operators
not or and Logical operators

Expression
It is a valid combination of operators,literals
and variable.
1. Arithmatic expression :- e.g. c=a+b
2. Relational expression :- e.g. x>y
3. Logical expression :- a or b
4. String expression :- c=“comp”+”sc”

Type
conversion
The process of converting the value of one data type (integer, string, float, etc.) to
another
data type is called type conversion.
Python has two types of type conversion.
Implicit Type
Conversion Explicit Type
Conversion
Implicit Type Conversion:
In Implicit type conversion, Python automatically converts one data type to another
data type. This process doesn't need any user involvement.
e.g.
num_int = 12
num_flo = 10.23
num_new = num_int + num_flo
print("datatype of num_int:",type(num_int))
print("datatype of num_flo:",type(num_flo))
print("Value of num_new:",num_new)
print("datatype of num_new:",type(num_new))
OUTPUT
('datatype of num_int:', <type 'int'>)
('datatype of num_flo:', <type 'float'>)
('Value of num_new:', 22.23)
('datatype of num_new:', <type
'float'>)

Type
conversion
Explicit Type Conversion:
In Explicit Type Conversion, users convert the data type of an object to
required
data type. We use the predefined functions like int(),float(),str()
etc. e.g.
num_int = 12
num_str = "45"
print("Data type of num_int:",type(num_int))
print("Data type of num_str before Type Casting:",type(num_str))
num_str = int(num_str)
print("Data type of num_str after Type Casting:",type(num_str))
num_sum = num_int + num_str
print("Sum of num_int and num_str:",num_sum)
print("Data type of the sum:",type(num_sum))
OUTPUT
('Data type of num_int:', <type 'int'>)
('Data type of num_str before Type Casting:', <type 'str'>)
('Data type of num_str after Type Casting:', <type 'int'>)
('Sum of num_int and num_str:', 57)
('Data type of the sum:', <type 'int'>)

math
module
It is a standard module in Python. To use mathematical functions of this
module,we have to import the module using import math.
Function Description Example
ceil(n) It returns the smallest integer greater than or equal to n. math.ceil(4.2) returns 5
factorial(n) It returns the factorial of value n math.factorial(4) returns 24
floor(n) It returns the largest integer less than or equal to n math.floor(4.2) returns 4
fmod(x, y) It returns the remainder when n is divided by y math.fmod(10.5,2) returns 0.5
exp(n) It returns e**n math.exp(1) return 2.718281828459045
log2(n) It returns the base-2 logarithm of n math.log2(4) return 2.0
log10(n) It returns the base-10 logarithm of n math.log10(4) returns 0.6020599913279624
pow(n, y) It returns n raised to the power y math.pow(2,3) returns 8.0
sqrt(n) It returns the square root of n math.sqrt(100) returns 10.0
cos(n) It returns the cosine of n math.cos(100) returns 0.8623188722876839
sin(n) It returns the sine of n math.sin(100) returns -0.5063656411097588
tan(n) It returns the tangent of n math.tan(100) returns -0.5872139151569291
pi It is pi value (3.14159...) It is (3.14159...)
e It is mathematical constant e (2.71828...) It is (2.71828...)

Control Statements
Control statements are used to control the flow
of execution depending upon the specified condition/logic.
There are three types of control statements.
1. Decision Making Statements
2. Iteration Statements (Loops)
3. Jump Statements (break, continue, pass)

Decision Making
Statement
Decision making statement used to control the flow
of execution of program depending upon condition.
There are three types of decision making statement.
1. if statements
2. if-else statements
3. Nested if-else statement

Decision Making
Statement
1. if statements
An if statement is a
programming statement that, if proved
true, performs a
or displays information.
conditional
function

Decision Making
Statement
1. if statements
Syntax:
if(condition):
statement
[statements]
e.g.
noofbooks =
2
if (noofbooks
== 2):
print
('You
have
')
print(‘two books’)
print(‘outside of if
statement’) Output
You have two books

Decision Making
Statement
1. if statements
Using logical operator in if statement
x=1
y=2
if(x
==
1
an
d
y==
2):
p
rint
(‘co
ndi
tio
n
ma
tci
ng Visit School Website for Regular Updates

Decision Making Statement
2. if-else Statements
If-else statement executes some code if the test expression is
true
(nonzero) and some other code if the test expression is false.

Decision Making Statement
2. if-else Statements
Syntax:
if(condition):
statements
else:
statements
e.g.
a=10
if(a
<
100)
:
pri
nt(
‘le
ss
tha Visit School Website for Regular Updates

Decision Making
Statement
The nested if...else statement allows you to check for multiple test
expressions and execute different codes for more than two
conditions.

Decision Making
Statement
Syntax
If (condition):
statement
s elif (condition):
s
tatements
else:
s
tatements
E.G.
num = float(input("Enter a
number: ")) if num >= 0:
if num == 0:
print("Zero")
else:
print("Positive number")
else:
print("Negative number")
OUTPUT
Enter a
number: 5 Visit School Website for Regular Updates

Iteration Statements
(Loops)
Iteration statements(loop) are used to execute a block
of statements as long as the condition is true.
Loops statements are used when we need to run same
code again and again.
Python Iteration (Loops) statements are of three type :-
1. While Loop
2. For Loop
3. Nested For Loops

(Loops)
1. While Loop
It is used to execute a block of statement as long as a
given condition is true. And when the condition become
false, the control will come out of the loop. The condition is
checked every time at the beginning of the loop.
Syntax
while (condition):
statement
[statements]
e.g.
x = 1
while (x <=
4): print(x)
x = x + 1
Output
1
2
3
4

Iteration Statements (Loops)
While Loop continue
While Loop With Else
e.g.
x = 1
while (x < 3):
print('inside while loop value of x is
',x) x = x + 1
else:
print('inside else value of x is ', x)
Output
inside while loop value of x
is 1 inside while loop value of
x is 2 inside else value of x is 5
*Write a program in python

While Loop continue
Infinite While
Loop
e.g.
x =
5
whil
e
(x
==
5):
pri
nt(‘i
nsid Visit School Website for Regular Updates

(Loops)
2. For Loop
It is used to iterate over items of any sequence, such as a
list or a string.
Syntax
for val in sequence:
statements
e.g.
for i in range(3,5):
print(i)
Outp
ut 3
4

(Loops)
2. For Loop continue
Example
programs for i in
range(5,3,-1):
print(i)
Outp
ut 5
4
rang
e()
Functi
on Visit School Website for Regular Updates

For Loop With Else
e.g.
for i in range(1, 4):
print(i)
else: # Executed because no break
in for print("No Break")
Output
1
2
3
4
No Break Visit School Website for Regular Updates

Nested For Loop
e.g.
for i in range(1,3):
for j in
range(1,11):
k=i*j
print (k, end='
') print()
Output
1 2 3 4 5 6 7 8 9
10

3. Jump Statements
Jump statements are used to
transfer the program's control from one location to
another. Means these are used to alter the flow of a loop
like - to skip a part of a loop or terminate a loop
There are three types of jump statements used in
python.
1.b
reak
2.continue

(Loops)
1.break
it is used to terminate the
loop.
e.g.
for val in
"string": if val
== "i":
break
print(val)
print("The
end")
Output
s

(Loops)
2.continue
It is used to skip all the remaining statements in the
loop and move controls back to the top of the loop.
e.g.
for val in
"init": if val
== "i":
continue
print(val)
print("The
end")
Output
n
t
The end

(Loops)
3. pass Statement
This statement does nothing. It can be used when a statement
is
required syntactically but the program requires no action.
Use in loop
while True:
pass # Busy-wait for keyboard interrupt (Ctrl+C)
In function
It makes a controller to pass by without executing any
code. e.g.
def myfun():
pass #if we don’t use pass here then error message
will be shown
print(‘my program')
OUTPUT Visit School Website for Regular Updates

(Loops)
3. pass Statement
continue e.g.
for i in 'initial':
if(i ==
'i'):
pass
else:
print(i
)
OUTP
UT
n
t
a
L
NOTE : continue forces the loop to start at the next

Revision-of-thehki-basics-of-python.pptx

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