Unit 1- Python- Features, Variables, Data Types, Operators and Expressions

ESIT135: PROBLEM SOLVING USING PYTHON
By,
Ms. Swapnali S. Gawali,
Asst. Prof. Computer Engineering
Sanjivani College of Engineering, Kopargaon
Sanjivani Rural Education Society’s
Sanjivani College of Engineering, Kopargaon-423 603
Department of Computer Engineering

UNIT-I CONTENT
Department of Computer Engineering, Sanjivani College of Engineering, Kopargaon
2

WHAT IS PYTHON?
• Python is a popular high-level, interpreted programming language
used in various applications
• Python is an easy language to learn because of its simple syntax
• Python can be used for simple tasks such as plotting or for more
complex tasks like machine learning
3

HISTORY OF PYTHON
• Created in 1990 by Guido van Rossum
• Named after Monty Python
• First public release in 1991
• comp.lang.python founded in 1994
• Open source from the start
• Considered a scripting language, but is much more
• Scalable, object oriented and functional from the beginning
• Used by Google from the beginning
• Increasingly popular
4

FEATURES OF PYTHON
5
Features of Python
1. Free and
Open Source
2. Easy to
code
3. Easy to
Read 4. Object-Oriented
Language
5. GUI Programming
Support
6. High-Level
Language
7. Portable
8. Easy to
Debug
9. Integrated and
Interpreted
10. Large Standard
Library

VALUES
• A value is one of the basic things a program work with, like
letter or a number.
• Example:
• 2 – Integer
• 42.0 – Floating Point
• ‘Hello’ – String
• We use variable to stored value.
6

DATA TYPE
• A data type defines the type of data stored in a variable.
• Python is a dynamically typed language, so we do not need to defined data types
while declaring.
• Data types are the classification or categorization of data items.
Department of Computer Engineering, Sanjivani College of Engineering, Kopargaon 7
Data Type
Numeric
Integer Complex
Number
Float
Dictionary Boolean Set Sequence
Strings Tuple
List

NUMERIC DATA TYPE
• It represents data that has a numeric value.
• Three Categories:
• Integer: int
• Float: float
• Complex Number: complex
• Integer: It contains negative and positive whole numbers. (without decimal
or fraction) Example:101,-319,20
• Float: It is real number with floating-point. Example: 1.5,4.5,3.5
• Complex Number: It is specified as (real part)+(imaginary part)j
example: -2+6j
8

SEQUENCE TYPE
• It is the ordered collection of similar or different data
types.
• Sequences used to stored multiple values in an organized
and efficient fashion.
• Three Categories:
• String: ' '," ",''' '''
• List: [ ]
• Tuple: ()
• String: It is a collection of one or more characters put in
‘single quote’,“double quote” and ‘‘‘ Triple quote”’
9

CONTINUE..
• List: It is like a array, which is ordered collection of data.
• It contains data of different types.
• The items are separated by comma(,) and enclosed with
in square bracket[].
• Example:A
list = [1,2,3,4,5,6]
fruit=["Apple", "mango", "banana"]
10

CONTINUE..
• Tuple: It is Like list, it also contains data of different types.
The items are separated by comma(,) and enclosed with in
square bracket().
• Tuple is immutable.
• Example:
fruit=("Apple", "mango", "banana")
tuple= (1,2,3,4,5)
11

BOOLEAN
• It provides two built in values,True and False.
• It determine the given value is true or false.
• It is denoted by class ' bool '.
• It also represented by ' 0 ' or ' 1 '
Example:
print(11>9)
a=200, b=33
print(a<b)
12

SET
• It is unordered collection of the data type.
• It is iterable, mutable and has unique elements.
• In it order of element is undefined.
• It is created by using built-in set() function, or a sequence of elements is
passed in curly braces and separated by comma.
• Example:
my_set = {1,2,3}
myset = {1.0, ' Hi ', (1,2,3,4)}
13

DICTIONARY
• It is an unordered set of a key-value pair of items.
• It is like an associative array or hash table where each key
stores a specific value.
• Key can store primitive data types.
• Value is an arbitrary Python Object.
• Example:
thisdict = {' brand ' : ' Maruti ', ' model ' : ' Swift ', ' year ' : 2000}
14

VARIABLES
• Variables are containers for storing data values.
• Unlike other programming languages, Python has no command for declaring a variable.
• A variable is created the moment we first assign a value to it.
• x = 5
y = "John"
print(x) 5
print(y) John
• Variables do not need to be declared with any particular type and can even change type
after they have been set.
• String variables can be declared either by using single or double quotes:‘John’ or”John”
15

RULES FOR CREATING VARIABLES IN PYTHON
• Following are rules for creating variables in Python
1.A variable name must start with a letter or the underscore character.
• example: a, name, _name_
2.A variable name cannot start with a number.
• Example:This is not allowed: 12a
3.A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ ).
• Example: Name, a12
4.Variable names are case-sensitive (name, Name and NAME are three different variables).
• Example:This A is different than a
5.The reserved words(keywords) cannot be used naming the variable.
• Example:This word not allowed
and, assert, break, class, continue, def, del, elif, else, except, exec, finally, for, from,
global, if, import, in, is, not, or, pass, print, raise, return, try, while 16

BASIC INPUT/OUTPUT IN PYTHON
• Input is any information provided to the program
– Keyboard input
– Mouse input
– File input
– Sensor
input (microphone, camera, photo cell, etc.)
• Output is any information (or effect) that a program produces:
– sounds, lights, pictures, text, motion, etc.
Output( on a screen, in a file, on a disk or tape, etc.)
17

OUTPUT FUNCTION
• print(): Used to print output.
• Example 1:
print ('HelloWorld’)
print ("Sanjivani")
print('''College of Engineering''')
18
Output
Hello World
Sanjivani
College of Engineering

OUTPUT FUNCTION (CONTINUE)
• Example 2:
name='Sonal’
rollno=10
print('Name is ',name)
print('Roll no is ',rollno)
Output
Name is Sonal
Roll no is 10
Example 3:
name='Sonal’
rollno=10
print('Name is ',name, 'Roll no is ',rollno)
Output
Name is Sonal Roll no is 10

• Example 4:
name='Sonal’
rollno=10
print(f'Name is {name}. Roll no is {rollno}.')
20
Output
Name is Sonal. Roll no is 10.

• Syntax of print()
print(object(s), sep=separator, end=end, file=file, flush=flush)
21
Parameter Description
object(s) Any object, and as many as you like.Will be converted to string before printed
sep='separator' Optional. Specify how to separate the objects, if there is more than one. Default is ' '
end='end' Optional. Specify what to print at the end. Default is 'n' (line feed)
file Optional.An object with a write method. Default is sys.stdout
flush Optional.A Boolean, specifying if the output is flushed (True) or buffered (False). Default
is False

• sep parameter: is used to specify the separator
between the strings.
• Example:
name='Sonal’
rollno=10
print(f'Name is {name}',f' Roll no is {rollno}',sep='.')
22
Output
Name is Sonal. Roll no is 10

• end parameter: . Specify what to print at the end.
• Example:
name='Sonal’
rollno=10
print(f'Name is {name}.',end=' ‘)
print(f' Roll no is {rollno}.')
23
Output
Name is Sonal. Roll no is 10.

INPUT FUNCTION
• Python input() function is used to take user input.
• By default, it returns the user input in form of a string.
• Syntax:
input('prompt message’)
• Example:
name=input('Enter your name’)
print(f'Name is {name}.’)
print(type(name))
24
Output
Enter your nameSonal
Name is Sonal.<class 'str'>

INPUT FUNCTION
• Example:
name=input('Enter your name’)
print(f'Name is {name}.’)
print(type(name))
rollno=int(input('Enter roll no’))
#int() use to convert string to integer value
print(f'Roll no is {rollno}.’)
print(type(rollno))
25
Output
Enter your nameSonal
Name is Sonal.
<class 'str’>
Enter roll no10
Roll no is 10.
<class 'int'>

OPERATORS AND OPERANDS
• Operators:Operators are symbol used to perform operations on variables
and values.
• Operands:
The values or variables that an operator acts on are called operands.
• A sequence of operands and operators is called expression.
Example: a+b-5
26
A + B - 5
Operands
Operator

DIFFERENT OPERATOR IN PYTHON
1. Arithmetic operators
2. Assignment operators
3. Comparison operators
4. Logical operators
5. Identity operators
6. Membership operators
7. Bitwise operators
27

ARITHMETIC OPERATORS
1. Arithmetic operators are used with numeric values to perform common
mathematical operations:
2. Assume x=10, y=5
28
Operator Name Example Output
+ Addition print(x+y) 15
- Subtraction print(x-y) 5
* Multiplication print(x*y) 50
/ Division print(x/y) 2.0
% Modulus print(x%y) 0
** Exponentiation print(x**y) 100000
// Floor Division x//y 2

PROGRAM
a=10
b=20
c=a+b
print(“Addition is ”,c)
c=a-b
print(“Subtraction is ”,c)
c=a*b
print(“Multiplication is ”,c)
c=a/b
print(“Division is ”,c)
29
Output:
Addition is 30
Subtraction is -10
Multiplication is 200
Division is 0.5

ASSIGNMENT OPERATORS
• Assignment operators are used to assign values to variables:
30
Operator Description
= Assign value of right side of expression to left side operand
+= Add and Assign: Add right side operand with left side operand and then assign to left operand
-= Subtract AND: Subtract right operand from left operand and then assign to left operand: True if both operands
are equal
*= Multiply AND: Multiply right operand with left operand and then assign to left operand
/= Divide AND: Divide left operand with right operand and then assign to left operand
%= Modulus AND: Takes modulus using left and right operands and assign result to left operand
//= Divide(floor) AND: Divide left operand with right operand and then assign the value(floor) to left operand
**= Exponent AND: Calculate exponent(raise power) value using operands and assign value to left operand

PROGRAM
a=10
b=20
print("a is ",a)
print("b is ",b)
a += 1
print("Add 1 to a ",a)
b -= 1
print("Subtract 1 from b ",b)
a **= 2
print("a square is ", a)
31
Output:
a is 10
b is 20
Add 1 to a 11
Subtract 1 from b 19
a square is 121

COMPARISON OPERATORS
• Comparison operators are used to compare two values:
32
Operator Name Example
== Equal a==b
!= Not Equal a!=b
> Greater than a>b
< Less than a<b
>= Greater than or equal to a>=b
<= Less than or equal to a<=b

PROGRAM
x=10
y=20
print(x==y)
print(x!=y)
print(x<y)
print(x>y)
print(x<=y)
print(x>=y)
33
Output:
False
True
True
False
True
False

LOGICAL OPERATORS
• Logical operators are used to combine conditional statements:
34
Operator Description Example
and Returns True if both statements are
true
x<5 and x<10
or Returns True if one of the statements
is true
x<5 or x<4
not Reverse the result, returns False if the
result is true
not(x<5 and x<10)

PROGRAM
x=10
y=20
print(x==y and x<y)
print(x!=y or x>y)
print(not(x<y))
35
Output:
False
True
False

IDENTITY OPERATORS
• Identity operators are used to compare the objects, not if they are
equal, but if they are actually the same object, with the same
memory location:
36
is Returns true if both variables are
the same object
a is y
is not Returns true if both variables are
not the same object
a is not y

PROGRAM
x=10
y=10
print(x is y)
print(x is not y)
37
Output:
True
False

MEMBERSHIP OPERATORS
• Membership operators are used to test if a sequence is
presented in an object:
38
in Returns True if a sequence with the specified
value is present in the object
a in b
not in Returns True if a sequence with the specified
value is not present in the object
a not in b

PROGRAM
x='sanjivani’
print('s' in x)
print('s' not in x)
print('S' in x)
print('S' not in x)
y='anji’
print(y in x)
print(x in y)
39
Output:
True
False
False
True
True
False

BITWISE OPERATOR
• In Python, bitwise operators are used to performing bitwise calculations on integers.
• The integers are first converted into binary and then operations are performed on bit by bit, hence the
name bitwise operators.
• Then the result is returned in decimal format.
40
OPERATOR DESCRIPTION SYNTAX
& Bitwise AND x & y
| Bitwise OR x | y
~ Bitwise NOT ~x
^ Bitwise XOR x ^ y
>> Bitwise right shift x>>
<< Bitwise left shift x<<

BITWISE AND OPERATOR
• Bitwise AND operator Returns 1 if both the bits are 1 else 0.
• Example:
a=10= 1010 (Binary)
b=4=0100 (Binary)
a&b = 1010
&
0100
=0000(Binary)
=0 (Decimal)
41

BITWISE OR OPERATOR
• Bitwise or operator Returns 1 if either of the bit is 1 else 0.
• Example:
a=10= 1010 (Binary)
b=4=0100 (Binary)
A|b = 1010
|
0100
=1110(Binary)
=14 (Decimal)
42

BITWISE XOR OPERATOR
• Bitwise xor operator: Returns 1 if one of the bits is 1 and the other is 0 else
returns false.
• Example:
a=10= 1010 (Binary)
b=4=0100 (Binary)
a^b = 1010
^
0100
=1110(Binary)
=14 (Decimal)
43

PROGRAM
a = 10
b = 4
print("a & b =", a & b)
print("a | b =", a | b)
print("a ^ b =", a ^ b)
44
Output:
a & b = 0
a | b = 14
a ^ b = 14

BITWISE RIGHT SHIFT
• Bitwise right shift: Shifts the bits of the number to the right and fills
0 on voids left( fills 1 in the case of a negative number) as a result.
• Similar effect as of dividing the number with some power of two.
• Example:
a=10= 0000 1010 (Binary)
a>>1=0000 0101 = 5
Example 2:
a= -10 = 1111 0110
a>>1 = 1111 1011 = -5
45

BITWISE LEFT SHIFT
• Bitwise left shift: Shifts the bits of the number to the left and fills 0
on voids right as a result.
• Similar effect as of multiplying the number with some power of two.
• Example:
a=10= 0000 1010 (Binary)
A<<1= 0001 0100 = 20
Example 2:
a= -10 = 1111 0110
A<<1 = 1110 1100 = -20
46

PROGRAM
a = 10
b = -10
print("a >> 1 =", a >> 1)
print("b >> 1 =", b >> 1)
a = 5
b = -10
print("a << 1 =", a << 1)
print("b << 1 =", b << 1)
47
Output:
a >> 1 = 5
b >> 1 = -5
a << 1 = 10
b << 1 = -20

STATEMENT
• A statement is an instruction that the Python interpreter can execute.
• Python statement ends with the token NEWLINE character. It means each
line in a Python script is a statement.
• There are mainly four types of statements in Python,
• print statements: print(“hello”)
• Assignment statements: a=100
• Conditional statements: if (a>10):
Print(“a is greater than 10”)
• Looping statements.: for x in range(6):
print(x)
48

MULTI-LINE STATEMENTS
Python statement ends with the token NEWLINE character.
But we can extend the statement over multiple lines using line continuation
character ().
This is known as an explicit continuation.
add=20+30+
50+60+
90
print(add)
Output: 250
49

IMPLICIT CONTINUATION:
We can use parentheses () to write a multi-line statement.
We can add a line continuation statement inside it.
Whatever we add inside a parentheses () will treat as a single statement even it is
placed on multiple lines.
addition = (10 + 20 +
30 + 40 +
50 + 60 + 70)
print(addition)
# Output: 280
50

COMPOUND STATEMENTS
• Compound statement contain (groups of) other statements; they affect or control the execution of those
other statements in some way.
• The compound statement includes the conditional and loop statement.
• if statement: t is a control flow statement that will execute statements under it if the condition
is true.Also known as a conditional statement.
• while statement:The while loop statement repeatedly executes a code block while a particular
condition is true.Also known as a looping statement.
• for statement: Using for loop statement, we can iterate any sequence or iterable variable.The
sequence can be string, list, dictionary, set, or tuple.Also known as a looping statement.
• try statement: specifies exception handlers.
• with statement: Used to cleanup code for a group of statements, while the with statement
allows the execution of initialization and finalization code around a block of code.
51

SIMPLE STATEMENTS
• Python has various simple statements for a specific purpose.
1. Expression Statement
2. The pass statement
3. The del statement
4. The return statement
5. The import statement
6. The continue and break statement
52

EXPRESSION IN PYTHON
• A combination of operands and operators is called an expression.
• The expression in Python produces some value or result after being interpreted by
the Python interpreter.
• Example:
r = a+b
res =10+a
result = 20+30
• An expression in Python can contain identifiers, operators, and operands.
• An identifier is a name that is used to define and identify a class, variable, or
function in Python.

TYPES OF EXPRESSION IN PYTHON
1.Constant Expressions
2.Arithmetic Expressions
3.Integral Expressions
4.Floating Expressions
5.Relational Expressions
6.Logical Expressions
7.Combinational Expression
54

CONSTANT EXPRESSION
• A constant expression in Python that contains only constant values is known
as a constant expression.
• In a constant expression in Python, the operator(s) is a constant.
• A constant is a value that cannot be changed after its initialization.
• Example:
a = 20 +10
55

ARITHMETIC EXPRESSION
• An expression in Python that contains a combination of arithmetic operators,
operands, and sometimes parenthesis is known as an arithmetic expression.
• The result of an arithmetic expression is also a numeric value
• Example:
x = c+d
x = c * a
56

INTEGRAL EXPRESSIONS
• An integral expression in Python is used for computations and type
conversion (integer to float, a string to integer, etc.).
• An integral expression always produces an integer value as a resultant.
• Example:
a = 5
b = 5.0
res = a + int(b)
57

FLOATING EXPRESSIONS
• A floating expression in Python is used for computations and type conversion
(integer to float, a string to integer, etc.).
• A floating expression always produces a floating-point number as a resultant.
• Example:
a = 5
b = 5.0
res = float(a) + b
58

RELATIONAL EXPRESSIONS
• A relational expression in Python can be considered as a combination of two or
more arithmetic expressions joined using relational operators.
• The overall expression results in either True or False (boolean result).
• We have four types of relational operators in Python (i.e. > , < , >= , <=)
(i.e.>,<,>=,<=).
• A relational operator produces a boolean result so they are also known
as Boolean Expressions.
• Example:
10+15>20
59

LOGICAL EXPRESSIONS
• As the name suggests, a logical expression performs the logical computation using logical
operators, and the overall expression results in either True or False (boolean result).
• Example:
a and b
a or b
a not b
a=3
b=3
if a>0 and b>0:
print(“a and b greater than zero”)
60

COMBINATIONAL EXPRESSIONS
• As the name suggests, a combination expression can contain a single or
multiple expressions which result in an integer or boolean value depending upon
the expressions involved.
• Example:
x = 5
y = 5
res = x + (2 *6)
61

BOOLEAN EXPRESSIONS
• A boolean expression is an expression that is either true or false.
• Example:
5 > 3
True
5 >9
False
62

CONVERSION FUNCTIONS
• Python defines type conversion functions to directly convert one
data type to another which is useful in day-to-day and competitive
programming.
• There are two types ofType Conversion in Python:
• Implicit Type Conversion
• Explicit Type Conversion
63

IMPLICIT TYPE CONVERSION
• In Implicit type conversion of data types in Python, the Python interpreter
automatically converts one data type to another without any user
involvement.
64
Program Output
x = 10
print("x is of type:",type(x))
y = 10.6
print("y is of type:",type(y))
z = x + y
print(z)
print("z is of type:",type(z))
x is of type: <class 'int'>
y is of type: <class 'float'>
20.6
z is of type: <class 'float'>

EXPLICIT TYPE CONVERSION
1.int(a, base): This function converts any
data type to integer. ‘Base’ specifies
the base in which string is if the data
type is a string.
2.float(): This function is used to
convert any data type to a floating-
point number.
3.tuple() : This function is used to convert
to a tuple.
4.set() : This function returns the type
after converting to set.
5.list() : This function is used to
convert any data type to a list type.
6.dict() : This function is used to convert a
tuple of order (key,value) into a
dictionary.
7.str() : Used to convert integer into a
string.
8.complex(real,imag) : This
function converts real numbers to
complex(real,imag) number.
65
In Explicit Type Conversion in Python, the data type is manually changed by the user as per
their requirement.
Various forms of explicit type conversion are explained below:

PROGRAM
x=5
print("x is of type:",type(x))
y=float(x)
print("y is of type:",type(y))
z=str(x)
print("z is of type:",type(z))
66
Output:
x is of type: <class 'int’>
y is of type: <class ‘float’>
z is of type: <class ‘str'>

PRECEDENCE OF OPERATORS
Solve this :
3 + 4 x 2 – 1
3 + 4 / 2 – 1
• BIDMAS
• BIDMAS, which stands
for Brackets, Indices, Division, Multiplication, Addition
and Subtraction.
67

• The operator precedence in Python is listed in the following table. It is in
descending order (upper group has higher precedence than the lower ones).
68
Priority Operator Meaning
1 () Parentheses
2 ** Exponent
3 +,-,~ Unary plus, Unary Minus, Bitwise NOT
4 *,/,//,% Multiplication, Division, Floor division, Modulus
5 +,- Addition, Subtraction
6 <<,>> Bitwise shift operators
7 & Bitwise AND
8 ^ Bitwise XOR
9 | Bitwise OR
10 ==, !=, >, >=, <, <=, is, is not, in, not in Comparisons, Identity, Membership operators
11 not Logical NOT
12 and Logical AND
13 or Logical OR

THANK YOU..
69

Unit 1- Python- Features, Variables, Data Types, Operators and Expressions

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