bytearray

Bytearray:

Bytearray is exactly same as bytes data type except its elements can be modified

Syntax:

1. create one list elements

2. type cast list element into bytearray elements

(1)Variable=[no1 ,no2,…]

Variable=bytearray(variable) #Type casting from list elements into bytearray elements

(2) Direct way to create

Variable=bytearray([no1,no2,….])

Example:

>>> a=[10,20,30] #list is created

>>> a=bytearray(a) #type casted from list elements into bytearray elements

>>> for i in a:print(i) #processing each elements where i varies from index 0th element to size-1 #elements.

10

20

30

Example for 2^nd way:

a=bytearray([10,20,30])

We can modify the values

a[0]=15 #we can modify

The previous session we have discussed so far:

Data types:

Data type	Description	Is immutable?	Example
int	Used to represent the numbers	Immutable	a=10
float	Used to represent decimal point numbers	Immutable	a=12.5
complex	Used to represent complex nos	Immutable	a=2+4j or a=2+4J
bool	Used to represent the logical values(True/False)	Immutable	a=True b=False
str	Used to represent collection of characters, should be enclosed within single quote or double quotes	Immutable	S=’ravi’ A=””Vij is a cool city””” b=”2+%j” c=’b’
Bytes	Used to represent a collection of byte values from 0 to 255	Immutable	a=bytes([120,20,30])
Bytearraya	Used to represent a collection of byte values from 0 to 255	Mutable	a=bytearray([10,20,30])
Range	Used to represent a range of values	Immutable	r=range(10) a=range(0,10) b=range(1,10,3)
List	Used to represent an ordered collection of elements(objcts)	Mutable	a=[10,20,30,40]
Tuple	Used to represent an ordered collection objects (elements)	Immutable	a=(2,4,5,6)
Set	Used to represent an unordered collection unique objects	Mutable	a={1,2,3,4}
Frozenset	Used to represent an unordered collection of objects	Immutable	s={1,2,’ravi’,4} a=frozenset(s) or a=frosenset({1,2,’ravi’,4})
Dict	Used to represent a group of key and value pair	Mutable	a={10:’ravi’,20:’sita’}
None	Used to represent no value or Nothing		def  sum():    print(“hi”) print(sum()) output: None

Constants in Python:

Defn: A constant is similar to a variable but its value can not be modified or changed in the course of the program execution.

The constant concept is not applicable in Python. It is possible in Java, C++ and C languages.

But A developer can indicate a variable as constant by writing its name in all upper case letters. 

For our convenience we use uppercase characters.

Example:

In mathematics, 'PI' value is 3.1714 which never changes and it is constant. 

PI=3.1714  #It is just convention but we can change the value.

Click here to see related videos

Next topic: Operators

Previous topic: byte data type

You may like the following topic:

Naming conventions

if…elif..else statement

if…elif..else:

Example 1

the marks obtained by a student in 3 subjects are input through the keyboard.

the students get a division as per the following rules:

75-100 distinction, 60--74 first class,50-59:2nd class,40--49:3rd class

#m,p,c=int(input("enter m,p,c marks"))#errr

m,p,c=(int(x) for x in input("enter m,p,c marks:").split())

avg=m+p+c/3;

if avg>=75:

    print("u passed in distinction %= ",avg)

elif avg>=60:

    print("U passed in First class %=",avg)

elif avg>=50:

    print("U passed in 2nd class %=",avg)

elif avg>=40:

    print("U passed in 3rd class %=",avg)

else:

    print("Failed,%=",avg)

output:

enter m,p,c marks:20 10 34

U passed in 3rd class %= 41.333333333333336

>>> 

Definition:

When we want to test multiple conditions and execute statements depending on those conditions. "if..elif..else statement" is useful.

Syntax:

if condition1:

    Statement

elif condition2:

    Statement2

elif conditon3:

   Statement3

….

else

    Default statement.

Based on the condition the corresponding action will be executed.

Explanation: condition 1 is True: statement 1 is executed

Remaining statements are not executed.

If condition 2 is True: only statement 2 is executed

If condition 3 is True: only statement 3 is executed

Ex2:

#Largest of two nos
a=int(input("enter 1st no"))
b=int(input("enter 2nd no"))

#Logic
if a>b:
    print("a is big")
else:
    print("b is big")
"""
output
enter 1st no2
enter 2nd no3
b is big
>>> """

Ex3:

#find the Largest of 3 nos

a=int(input("Enter 1st no"))

b=int(input("enter 2nd no"))

c=int(input("enter 3rd no"))

#Logic

if a>b and a>c:

    print("Big no is a=",a)

elif b>c:

    print("Big no is b=",b)

else:

    print("Big no is c=",c)

"""

Note1:

Enter 1st no 10

enter 2nd no 20

enter 3rd no 30

Note2:

Enter 1st no 40

enter 2nd no 20

enter 3rd no 5

Big no is a= 40

>>>

"""

Related video: https://www.youtube.com/watch?v=VozU5n3ouHM&feature=youtu.be

Next Topic:  Loops in Python
Previous Topic: if else statement