PYTHON PROGRAMMING PROBLEM SOLVING PPT DOCUMENTS PPT

Unit 1
Part C : Basics of Python
Programming
By Prof. S.S.Wadnere
1. Features of Python,
2. History and Future of Python
3. Writing and executing Python
4. Program Literal constants, variables and identifiers,
Data Types, Input operation, Comments, Reserved
words, Indentation, Operators and expressions,
Expressions in
Python. SNJB KBJ COE, Chandwad

History of
Python
1. Python is an interpreted, high-level, general-
purpose programming language.
2. Created by Guido van Rossum and first released in
1991
3. Python 2.0, released in 2000
4. The Python 2 language, i.e. Python 2.7.x, was
officially discontinued on January 1, 2020
5. A global community of programmers develops
and maintains python.
6. Python 3.0 was released on 3 December 2008. It was
a major revision of the language that is not
completely backward-compatible.
Guido van
Rossum at
OSCON 2006
SNJB KBJ COE, Chandwad

•Data Science.
•Machine Learning.
•Web Development.
•Computer Science Education.
•Game Development.
•Medicine and Pharmacology.
•Biology and Bioinformatics.
•Computer Vision and Image Processing.
Python in Real-World Scenarios
Python is used in virtually every industry and scientific field that you can imagine,
including:
• Neuroscience and Psychology.
• Astronomy.
• Other areas such as robotics,
autonomous vehicles, business,
meteorology, and graphical user interface
(GUI) development.

Python IDLE (Integrated Development and Learning Environment)
Shell
Interactive
Mode
Script
Mode
Writing Python Programs
Step 1: Open an editor
Step 2: Write the
instructions (Program
Code)
Step 3: Save it as a file

Literals Constants
• The value of literal constant can used directly in program.
• It is a constant because its value cannot be changed.
• Ex. 7, 8.4, ‘A’ and “Hello”
Numbers
• Number as name suggests, refer to a numeric value.
• Four type of number used in python program.
• Integers
• Long Integers
• Floating Point
• Complex number
2380
467838675843L
23.57 or 91.5E-2
numbers of a+bi form (Like -3 + 7i)

String Literal
• String is group of characters, also known as text.
• We can use string using
• Single Quotes (‘)
• Double Quotes (“)
• Triple Quotes (“’)
• All spaces and tabs within string are preserved in quotes.
String literal concatenation
•Python concatenates two string that places side by
side Raw String
• String without any escape sequence, display exactly as
spacified.
Unicode
• Unicode is standard way of writing international text.

Boolean Literal
• Boolean data type variable can have one of the two value – True or
False.
• When you compare two values, the expression is evaluated and
Python returns the Boolean answer.
Ex.
print(10 > 9)
print(10 == 9)
print(10 < 9)
Output: True
Output: False
Output: False

Variable
• Variable are reserved memory location that store value.
• Every variable assigned a name which can be used to refer to the
value later in the program.
• Variable can hold value of different types called data types.

Identifiers
• Identifiers Known as name given to identity something.
• This something can be variable, function, class, module or other user
defined objects.
• For naming there are some basic rules,
• First character must be underscore _ or letter( alphabets ).
• Rest of the identifier name can be _ , letter or numbers.
• Identifier names are case-sensitive
• Any other symbols are not allowed with in identifiers
•

Assigning or Initializing Value to Variables
• In python programmers need not explicitly declare variable to reserve
memory space.
• The declaration done automatically when a value assigned to the
variable using the = operator.
• You can reassign variables as many times as you want to change the
value stored in them.
•Variable can be deleted by using del
statement. Multiple Assignment
• Python allow single value to multiple variables
• Ex. sum = flag = a = b = 0
• Ex. sum , a , b , mesg = 0 ,39.45 , 52, ”Result”

Print Function
• The print() function prints the specified message to the screen, or
other standard output device.
• The message can be a string, or any other object, the object will be
converted into a string before written to the screen.
Example :
print("Hello World")
x = ("apple", "banana", "cherry")
print(x)

Python 3.6 uses the input() method.
Python 2.7 uses the raw_input()
method.
Input Function
• Input method can use to take input from users.
• Input function always take user input in the form of string only.
• User can convert the data type using casting functions.
Example:
a = input(“Enter the number: ”)
B = int(input(“Enter the number: ”))
 Write a python program to addition of two numbers using input function

Built-in format()function
• The format () function produces a numeric string of a floating point
value rounded to a specific number of decimal places.
# Without using format()
>>>16/3
5.333333333333333
# Using format()
>>> format(16/3,'.2f')
'5.33'
• Simple Operation of number
• Division by zero
• Dividing two integers
• Quotient and Remainder

Type Conversion
• In Python certain operations that involves different types of data. To perform
this operation data type conversion is required.
Function Description
int(y) It converts y to an integer.
float(y) It converts y to a floating-point number.
long(y) It converts y to an float.
str(y) It converts y to a string.
tuple(y) It converts y to a tuple.
list(y) It converts y to a list.
set(y) It converts y to a set.
dict(y) It creates a dictionary and y should be a sequence of (key,value) tuples.
ord(y) It converts a character into an integer.
hex(y) It converts an integer to a hexadecimal string.
oct(y) It converts an inteSgNeJBrKtBoJ COaEn, Choacndtwaaldstring

Escape Sequences
• Some characters cannot be directly included in a string.
• Such character must be escaped by placing a backslash before them.
Escape
Sequence Description Example Output
Prints Backslash print ""
` Prints single-quote print "'" '
" Prints double quote print """ "
a Ringing the bell alert sounds ( eg. xterm ) print "a" N/A
b Removes previous character print "ab" + "b" + "c" ac
n ASCII linefeed ( LF ) print "hellonworld"
hello
world
t ASCII horizontal tab (TAB). PrinStNsJBTKABJBCOE,
Chandwad
print "t* hello" * hello

Comments
• Comments are non-executable statements in program.
• They are just added to describe the statements in the program code.
• All characters following by # consider as comments.
•A program can have any number of
comments. Ex.
#This is a comment
print("Hello, World!")
Multi line Comments
Ex.
"""
This is a comment
written in
more than just one line
"""
print("Hello, World!")

Reserved Words
• This word are which have pre-defined meaning.
• We can not be use this reserved word for naming of identifiers.
and assert in
del else raise
from if continue
not pass finally
while yield is
as break return
elif except def
global import for
or print lambda
with SNJBcKlBaJsCsOE,
Chand
wad try
e

Indentation
• Whitespaces and tabs that are used at the beginning of a statement.
• The statements with the same indentation belong to the same group
called a suite.
• Statements in a block must have same indentation level.
•
if a==1:
print(a)
if b==2:
print(b)
print('end')

Operators and Expressions
• Operators are the constructs that are used to manipulate the value of
operands.
• Python support different types of operators
• Arithmetic operators
• Comparison (Relation) operators
• Assignment operators
• Logical operators
• Unary operators
• Bitwise operators
• Membership operators
• Identity operators

• Arithmetic Operators
Operator Description Example
+ Adds two operands. A + B = 30
− Subtracts second operand from the first. A − B = -10
* Multiplies both operands. A * B = 200
/ Divides numerator by de-numerator. B / A = 2
% Modulus Operator and remainder of after an
integer division.
B % A = 0
// Floor Division: Divides the operands and
returns the quotient.
12//5 = 2
** Exponent: Perform exponential calculation. 3**2 = 9

• Comparison Operators : Used to perform comparison. Relational operators
always results in Boolean value either 1 TRUE or 0 FALSE. Following is the list
Operator Description Example (A=20 B=50)
== Checks if the values of two operands are equal or
not.
(A == B) is not true.
!= Checks if the values of two operands are equal or
not.
(A != B) is true.
> Checks if the value of left operand is greater than the
value of right operand.
(A > B) is not true.
< Checks if the value of left operand is less than the
value of right operand
(A < B) is true.
>= Checks if the value of left operand is greater than or
equal to the value of right operand.
(A >= B) is not true.
<= Checks if the value of left operand is less than or
equal to the value of right operand. If yes, then the
condition becomes true.
(A <= B) is true.

• Assignment Operators
= Simple assignment operator C = A + B will assign the value
of A + B to C
+= Add AND assignment operator. C += A is equivalent to C = C +
A
-= Subtract AND assignment operator. C -= A is equivalent to C = C -
A
*= Multiply AND assignment operator. C *= A is equivalent to C = C *
A
/= Divide AND assignment operator. C /= A is equivalent to C = C /
A
%= Modulus AND assignment operator. C %= A is equivalent to C = C
% A

• Bitwise Operators : are used to perform binary arithmetic.
Operator Use Example
~ Not ~a
& AND a&b
| OR a|b
^ Xor a^b
<< Shift left a<<2
>> Shift Right b>>2
p q p & q p | q p ^ q
0 0 0 0 0
0 1 0 1 1
1 1 1 1 0
1 0 0 JB KBJ CO1E,
Chandw
ad 1

• Logical Operators :
and
Called Logical AND operator. If both the
operands are non-zero, then the condition
becomes true.
(A and B)
is false.
or
Called Logical OR Operator. If any of the two
operands is non-zero, then the condition
becomes true.
(A or B)
is true.
not
Called Logical NOT Operator. It is used to reverse
the logical state of its operand. If a condition is
true, then Logical NOT operator will make it
false.
not(A and B)
is true.

Membership Operator
in Returns True if a sequence with the specified
value is present in the object
x in y
not in Returns True if a sequence with the specified
value is not present in the object
x not in y
This operator test for membership in a sequence such as string, list ,or tuples.
Identity Operator
is Returns true if operands or values on both
sides is same
x is y
is not Returns true if operands or values on both
sides of the operator does not point to the
same object SNJB KBJ COE, Chand
x not is y
wad

Python Operators Precedence and Associativity
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'
^ | 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

Expressions
• An expression is any combination of symbols (like variables, constants and operators).
• In Python, an expression must have at least one operand and can have one or more operators.
• On evaluating an expression, we get a value.
Based on the position of operator in an expression
Infix Expressions: The operator placed in between the operands. Example: a = b – c
Prefix Expressions: The operator placed before the operands. Example: a = - 10
Postfix Expressions: The operator placed after the operands. Example: a = 10 -

Expressions
Based on the position of operator in an expression
Constant Expressions: Use Only constants. Example: 8 + 9 – 2
Integral Expressions: produces an integer result after evaluating the expression. Example: a = 10
Floating Point Expressions: Produces floating point results. Example: a * b / 2
Relational Expressions: Returns either true or false value. Example: c = a>b
Logical Expressions: Involve relational operator, returns True or False. Example: a>b && y! = 0
Bitwise Expressions: Manipulates data at bit level. Example: x = y&z
Assignment Expressions: Assigns a value to a variable. Example: c = a + b or c = 10

Expressions in Python
• In Python, operators are special symbols to perform some operations.
• The values that an operator acts on are called operands.
Type of Expressions
• Infix Expression : operator place between the operands. Ex. a = b
- c
• Prefix Expression : operator place before the operands. Ex. a = - b
c
• Postfix Expression : operator place after the operands. Ex. a = b c
-
Data type based expressions
• Assignment Expression : a = 10 or b = 20
• Constant Expression : Ex. 4 + 2 - 3
• Integral Expression : Ex. c = a + b
• Floating Point Expression : Ex. a * b / 2

Operations on Strings
Examples:
• Concatenation
• Multiplication or String Repetition
• Slice a String

Slice Operations on Strings
• You can extract subsets of strings by using the
slice
operator ([ ] and [:]).
• You need to specify index or the range of index of
characters to be extracted.
• The index of the first character is 0 and the index of the
last character is n-1, where n is the number of characters
• If you want to extract characters starting from the end of
the string, then you must specify the index as a
negative number. For example, the index of the last
character is -1.
Examples:

Examples:

Programming Examples
• Write a program to enter a number and display its HEX and Octal equivalent.
• Write a program to calculate area of triangle using Heron’s formula.
• Write a program to swap two numbers.
• Write a program that accepts an object’s mass (in kilograms) and velocity (in
meters per second) and displays its momentum.
• Write a program to calculate seconds in day.
• Write print function for following output.
'/'/'/'
'/'/'/' '/'/'/'
'/'/'/' SNJB KBJ COE, Chandwad

PYTHON PROGRAMMING PROBLEM SOLVING PPT DOCUMENTS PPT

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