Python basics

POWERED BY
RANA ALI
PYTHON PROGRAMMING
LANGUAGE (OVERVIEW)

The Python Programming Language
Audience
• Having basic understanding of programming or worked
on any High Level language like C, JAVA, or C ++, etc
At the end you will be able:
• Understand the significance of Python Programming
• Familiarize with the Python IDE Environment
• Understand the Input and Output operations in Python
• Use variables in Python language

What is Python Programming
• Python was developed by Guido van Rossum
(a Dutch programmer) in 1991
• Python is a High Level Language (whereas C and
Java are not High Level Language)
• Python has a design philosophy that emphasizes
Code Readability
• The syntax allows programmer to express
concepts in fewer lines of code than might be
used in languages such as C++, Java etc

Why Python Programming
According to IEEE Spectrum the top Programming Languages in
2017 are:
http://spectrum.ieee.org/computing/software/the-2017-top-programming-languages

Because it Easy to learn and use: Its simple
syntax is very accessible to programming
novices and will look familiar to anyone with
experience in Matlab, C/C++, Java. Also
Python has powerful libraries

• Because it is FREE
There is no worried of buying the key and or unethical use of software by
cracking its key
• Because it is Open Source
In the Open Source software the
source code, blue print and
documentation are freely available to
public. The software developer
voluntarily put their part to add the
features in the software

Python has vast development implementation

Python Cross-compilers to other languages

Python Web development frameworks

Working on Python IDLE
Download Python IDLE 2.x or 3.x from Python Software Foundation
Website for Free

Python IDLE Environment
IDLE (Integrated Development Learning Environment)
• IDLE has multi-window text editor with syntax highlighting,
auto-completion, smart indent
• The Shell window execute command at the statement
complete
• User code written in Text Editor window

Some Useful command for Python IDLE Shell
window
• Alt + p to retrieve Previous Command
• Alt + n to retrieve Next Command
• To get help of instruction or command use
help(instruction)
Python IDLE Environment

My First Python Program
Open Python IDLE Shell window and write the following
instruction
A print is an output instruction use to display string or
data value on screen
print(“HELLO")
Note: Program contain no header file, no main() function,
no semi column at instruction end, even you write string
in single quotation mark. BUT one thing common with
other programming language that is Case Sensitive
print(‘HELLO‘)

Output Instruction
Escape Sequence Working
Backslash ()
' Single quote (')
" Double quote (")
n ASCII Linefeed (LF)
t ASCII Horizontal Tab (TAB)
Example:
>>>print('BackslashtTabnNewline')
Backslash Tab
Newline`
The following are the Escape Sequence use with
print instruction

Python Data types
Python has five standard data types
• Numbers(Integer and Float)
• String
• List (Array)
• Tuple (Constant Array)
• Dictionary
Variable Number type:
• Integer (whole number)
• Float (decimal point number)
• Character/String (ASCII format)
• Boolean (True and False)

Python Variable
• Type of Variable: Check the type of Variable
• Deleting Variable: Delete the declare variable
Syntax: del(variable_name)
>>> a = 2
>>> print(a)
2
>>> del(a)
>>> print(a)
NameError: name 'a' is not defined
Variable value Type command Result
a=2 type(a) <class 'int'>
b=3.5 type(b) <class 'float'>
c=’f’ type(c) <class 'str'>
d=’abc123’ type(d) <class 'str'>
type(True) <class 'bool'>
type(False) <class 'bool'>

Python is an Interpreter Language
Working Compiler Interpreter
Converting code Convert whole code Step by step
Translation time Slow Fast
Execution time Fast Slow
Programming Languages
C, Visual Basic, Java,
LabView etc
Python, Matlab, PHP, MS
Excel etc

Python Interpreter Example
In Interpreter, if code contains error it may run
partially and stop when error occurs. In the
following code Error is present in line number 7 that
is “d=B” where ‘B’ is not define before, so program
runs and execute up to that line.

Input Instruction
• Input Instruction: To take an input from user through
keyboard input() command is used, this instruction take
input from keyboard in the form of ASCII character and
store it the variable.
• Syntax:
take_input = input(1 Argument)
• Example:
name = input('Enter your name =')
age = input('Enter your age = ')
print('Your name is ', name , ',and your age is = ',age)

Python Version
• Python Version 1 is obsolete now
• Python Version 2 and Python Version 3 is active
• The Python 2 is old version but retain for programming
because lots of module was developed on it which not
work with Python 3
• There is only some difference in execution of
instructions other wise both have same working

Difference between Python 2 and Python 3
Output Instruction
Python 2 Python 3
Python 2 allows to write the print
instruction argument with in Round
bracket ( and) or with out it.
The argument of the print instruction must
written with in Round bracket ( and)
>>> print('String') #Allow
String
>>> print("String") #Allow
String
>>> print 'String' #Allow
String
>>> print "String" #Allow
String
>>> print('String') #Allow
String
>>> print("String") #Allow
String
>>> print 'String' #NotAllow
SyntaxError: Missing parentheses in call to 'print‘
>>> print "String" #NotAllow
SyntaxError: Missing parentheses in call to 'print‘

Input Instruction
Python 2 Python 3
input(prompt) raw_input(prompt) Input(prompt)
It keeps the type of user
enter data
Automatically update the
Input variable to the user
enter data
Always take data in the
string format regardless of
the user enter data
Syntax:
Input_variable = input(prompt)
Input_variable data type is
same as user enter data
Syntax:
Input_variable is String
Syntax:
Input_variable is String

Input Instruction Example
Python 2 Python 3
input(prompt) raw_input(prompt) Input(prompt)
>>> a = input("Enter = ")
Enter = 12
>>> type(a)
<type 'int'>
Enter = 12.12
>>> type(a)
<type 'float'>
Enter = "Ab12"
>>> type(a)
<type 'str'>
Enter = Ab12
NameError: name 'Ab12' is not
defined
>>> a = raw_input("Enter = ")
Enter = 12
>>> type(a)
<type 'str'>
Enter = 12.12
>>> type(a)
<type 'str'>
Enter = "Ab12"
>>> type(a)
<type 'str'>
Enter = Ab12
>>> type(a)
<type 'str'>
Enter = 12
>>> type(a)
<class 'str'>
Enter = 12.12
>>> type(a)
<class 'str'>
Enter = "Ab12"
>>> type(a)
<class 'str'>
Enter = Ab12
>>> type(a)
<class 'str'>

(problem and its solution)
Python 2 Python 3
Program
num = input('Enter a number = ')
print num,‘x 3 = ',num * 3
num = input('Enter a number = ')
print( num,‘x 3 = ',num * 3 )
Output
Enter a number = 5
5 x 3 = 15
Enter a number = 5
5 x 3 = 555
Observation: the num is integer so
number 5 x 3 is number 15
Observation: the num is String so String 5
x 3 is three times of number 5
The problem in the output of Python 3 is
solved in later slides

Change the variable type
Function Description
Example
Instruction Output
str(x) Converts object x to a string representation.
str(75)
str("25.25")
‘75’
'25.25'
int(x) Converts object x to a integer number.
int(35.26)
int(100.101 )
35
100
float(x) Converts object x to a float number.
float(35)
float(100)
35.0
100.0
list(s) Converts s to a list.
list(range(5,10))
list(range(1,10,2))
[5, 6, 7, 8, 9]
[1, 3, 5, 7, 9]
tuple(s) Converts s to a tuple.
tuple(range(5,10))
tuple(range(1,10,2))
(5, 6, 7, 8, 9)
(1, 3, 5, 7, 9)
dict(d)
Creates a dictionary. d must be a sequence
of (key,value) tuples.
chr(x) Converts an integer to a character.
chr(65)
chr(97)
'A‘
‘a’
ord(x) Converts a single character to its ASCII (integer value)
ord('A')
ord(‘a')
65
97
hex(x) Converts an integer to a hexadecimal string.
hex(16)
hex(100)
'0x10‘
'0x64'
oct(x) Converts an integer to an octal string.
oct(9)
oct(50)
'0o11‘
'0o62'

Exercise
Rewrite the following program in Python 3 with
correct output display
Without changing Variable Type Changing Variable Type
num = input(“Enter a number = “)
print( num,”x 3 = “,num * 3 )
num = input(“Enter a number = “)
print( num,“x 3 = ",int(num) * 3 )
3 x 3 = 333 3 x 3 = 9

Python IDEs
• Python IDLE
• PyCharm
• Sublime Text
• Atom
• Geany
• Anjuta
• Eric
• Komodo IDE
• KDevelop
• Ninja-IDE
•
• Spyder

Integer Operation
bit_length(...)
Number of bits necessary to represent self in binary
Example: >>> (37).bit_length() 6
>>> int_num.bit_length() 2
bin(…)
Return binary of the integer
Example: >>> bin(37) '0b100101'
>>> bin(25) '0b1111111'
Denominator The denominator of a rational number in lowest terms
Imag The imaginary part of a complex number
numerator The numerator of a rational number in lowest terms
real The real part of a complex number
conjugate(...) Returns self, the complex conjugate of any int.
to_bytes(...) Return an array of bytes representing an integer.

Float Operation
float.fromhex (...)
Create a floating-point number
from a hexadecimal string.
Example: >>>float.fromhex('0x1.ffffp10') 2047.984375
float.hex(…)
Return a hexadecimal representation of a floating-point number
Example: >>>3.14159.hex() '0x1.921f9f01b866ep+1'
is_integer(...)
Return True if the float is an integer
Example: >>> num = 5.5
>>> num.is_integer() False
>>> num = num - 0.5 # remove floating value
>>> num.is_integer() True
as_integer_ratio(...)
Return a pair of integers, whose ratio is exactly equal to the original float and
with a positive denominator.
Example: >>> (10.0).as_integer_ratio() (10, 1)
>>> (0.0).as_integer_ratio() (0, 1)
>>> (-.25).as_integer_ratio() (-1, 4)
conjugate(...) Return self, the complex conjugate of any float.
imag The imaginary part of a complex number
Real The real part of a complex number

String Operation
len(string) Return length of string
capitalize(...)
Return a capitalized version of S, i.e. make the first character have upper
case and the rest lower case.
title(...)
Return a title cased version of S, i.e. words start with title case characters,
and all remaining cased characters have lower case.
lower(...) Return a copy of the string S converted to lowercase.
upper(...) Return a copy of S converted to uppercase.
casefold(...) Return a version of S suitable for caseless comparisons
islower(...)
Return True if all cased characters in S are lowercase and there is at least one
cased character in S, False otherwise.
isupper(...)
Return True if all cased characters in S are uppercase and there is at least
one cased character in S, False otherwise.
isnumeric(...) Return True if there are only numeric characters in S, False otherwise.
isdecimal(...) Return True if there are only decimal characters in S, False otherwise
isdigit(...)
Return True if all characters in S are digits and there is at least one character
in S, False otherwise.

a = input("Enter your name:")
print("Lower Case of Enter string = " ,a.lower())
print("Upper Case of Enter string = " , a.upper())
print("Title Case of Enter string = " , a.title())
print("Length of Enter string = " , len(a))
print("Your Enter string is Alpha = " , a.isalpha())
print("Your Enter string is Decimal = " , a.isdecimal())
print("Your Enter string is Digit = " , a.isdigit())
print("Your Enter string is in Lower case = " , a.islower())
print("Your Enter string is in Upper case = " , a.isupper())
print("Your Enter string is in Title case = " , a.istitle())
Output 1:
Enter your name:Hamdard university
Lower Case of Enter string = hamdard university
Upper Case of Enter string = HAMDARD UNIVERSITY
Title Case of Enter string = Hamdard University
Length of Enter string = 18
Your Enter string is Alpha = False
Your Enter string is Decimal = False
Your Enter string is Digit = False
Your Enter string is in Lower case = False
Your Enter string is in Upper case = False
Your Enter string is in Title case = False
Output 2:
Enter your name:123456
Lower Case of Enter string = 123456
Upper Case of Enter string = 123456
Title Case of Enter string = 123456
Length of Enter string = 6
Your Enter string is Alpha = False
Your Enter string is Decimal = True
Your Enter string is Digit = True
Your Enter string is in Lower case = False
Your Enter string is in Upper case = False
Your Enter string is in Title case = False
String Operation Example

Comparing Python with C/C++
Programming Parameter Python Language C/C++ Language
Programming type Interpreter Compiler
Programming Language High level Language Middle level Language
Header file import #include
Code block Whitespace Indentation
Code within curly bracket
{ code}
Single line statement
termination
Nothing Semicolon ;
Control flow (Multi line)
statement termination
Colon : Nothing
Single line comments # comments //comments
Multi-line comments
‘’’
Comments lines
‘’’
/*
Comments lines
*/
If error code found Partial run code until find error
Did not run until error is
present
Program length Take fewer lines Take relatively more lines

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