Python Programming Language Workshop session 3

1. Faculty of Engineering Science & Technology(FEST)
Hamdard Institute of Engineering Technology(HIET)
HAMDARD UNIVERSITY
Instructor
ABDUL HASEEB
HANDS-ON WORKSHOP ON PYTHON
PROGRAMMING LANGUAGE
Faculty Development Program (Session-10)
DAY-3

2. The Python Programming Language
Day 2 Workshop Contents
• Error handling
• List (Array)
• Random Number

3. Error Handling
Exception is an ambiguity or error which occur during the execution
of the program. The Exception must be handle in code other wise it
effect the flow of program execution.
Syntax try except/else and finally
try:
..........operation
except Exception_1:
..........if there is Exception, then execute this block
except Exception_2:
..........if there is Exception, then execute this block
else:
..........if there is no exception then execute this block
finally:
..........this would always be executed

4. Program 1 (No Error Handling statement)
Enter a = 5
Enter b = 2
Result 2.5
Enter a = 3.6
Enter b = 4.2
ValueError: invalid literal for int() with base 10: '3.6'
Enter a = A
Enter b = B
ValueError: invalid literal for int() with base 10: 'A'
Enter a = 7
Enter b = 0
ZeroDivisionError: division by zero
num1 = input("Enter a = ")
num2 = input("Enter b = ")
result = int(num1)/int(num2)
print('Result',result)
Program
Output 2
Output 3
Output 4
Output 1

5. Program 1 (No type of Exception use)
num1 = input("Enter a = ")
num2 = input("Enter b = ")
try:
result = int(num1)/int(num2)
except:
print('error')
else:
print('Result',result)
finally:
print('Thank you')
Result 1
Enter a = 5
Enter b = 2
Result 2.5
Thank you
Result 2
Enter a = 3.6
Enter b = 4.2
error
Thank you
Result 3
Enter a = 7
Enter b = 0
error
Thank you

6. Program 2 (with type of Exception)
num1 = input("Enter a = ")
num2 = input("Enter b = ")
try:
result = int(num1)/int(num2)
except ZeroDivisionError:
print('Number cannot divisibly by 0')
except ValueError:
print('Please enter integer number')
else:
print('Result',result)
finally:
print('Thank you')
Result 1
Enter a = 5
Enter b = 2
Result 2.5
Thank you
Result 2
Enter a = 3.6
Enter b = 4.2
Please enter integer number
Thank you
Result 3
Enter a = 7
Enter b = 0
Number cannot divisibly by 0
Thank you

7. Exercise
Insert Exception in the following Infinite loop
Program
while True:
print("Hamdard University")
Note: To break Infinite loop use Ctrl + c
Output
Hamdard University
Hamdard University
Hamdard University
Traceback (most recent call last):
File "C:UsersHomeDesktoptemp.py", line 132, in <module>
print("Hamdard University")
KeyboardInterrupt print("Hamdard University")

8. Exercise Solution
Program
try:
while True:
print("Hamdard University")
except KeyboardInterrupt:
print("Thank you“)
Output
Hamdard University
Hamdard University
Hamdard University
Hamdard University
Thank you

9. Example
The following program ask user to enter his height in cm that is integer
value, if user enter in feet (floating value) then program will take his height
in feet and proceed further program
try:
num = int(input("Enter your height in cm = "))
print('Your height in cm is =',num)
except ValueError:
num = float(input("Ok! you want to enter in feet = "))
print('Your height in feet is =',num)
finally:
print('Thank you')
Output:
Enter your height in cm = 36.45
Ok! you want to enter in feet = 36.45
Your height in feet is = 36.45
Thank you

10. Exception with while loop
The following program take Integer value from user. If user enter an Integer value then program proceed
but if user enter non-integer value then it will ask again until enter correct value
Program
key_check = True
while(key_check == True):
try:
key = int(input("Enter a number ="))
except:
print('You have press an invalid digit')
key_check = True
else:
key_check = False
print('You have enter number',key)
Output
Enter a number =a
You have press an invalid digit
Enter a number =b
You have press an invalid digit
Enter a number =c
You have press an invalid digit
Enter a number =3
You have enter number 3

11. LIST (Array)
• Two types of Array
• Static Array (in C)
• Dynamic Array( in Python)
Example in C (static Array)
float balance[5] = {10.0, 2.0, 3.4, 7.0, 50.0};
balance[4] = 50.0; //Update array value
char greeting[6] = {'H', 'e', 'l', 'l', 'o', '0'};
char greeting[] = "Hello"; // Or it can be written as
Example of Array in Python (Dynamic Array)
My_data = ['physics', 'chemistry', 1997, 2000]

12. Example
Example:
a=[0,0,0] #creating list of 3 elements
a[0] = input(“Enter name 1= ”)
a[1] = input(“Enter name 2= ”)
a[2] = input(“Enter name 3= ”)
print(‘Name 1 is’, a[0] , ‘ Name 2 is’, a[1] , ‘ Name 3 is’, a[2])

13. LIST Example
a = [0,1,2,3,4,5,6,7,8,9] #Making list
a[2] = 2 # Value of index 2
a[4] = 4 # Value of index 4
a[3:] = [3, 4, 5, 6, 7, 8, 9] # All values from(after) index 3
a[:7] = [0, 1, 2, 3, 4, 5, 6] # All values before index 7
a[3:7] = [3, 4, 5, 6] # All values from index 3 to index 7

14. Forward and Backward Indexing
a = [1,2,3,4,5]
a[0]
1
a[1]
2
a[2]
3
a[3]
4
a[4]
5
a = [1,2,3,4,5]
a[-1]
5
a[-2]
4
a[-3]
3
a[-4]
2
a[-5]
1
Forward Indexing Reverse Indexing

15. List-append
a = []
[]
a.append(2)
[2]
a.append(3.5)
[2, 3.5]
a.append('xyz')
[2, 3.5, 'xyz']
2 2
2 3.5 3.5
2 3.5 xyz ‘xyz’
list.append(object): Append object to end

16. list - clear
a = [0,1,2,3,4,5]
[0, 1, 2, 3, 4, 5]
a.clear()
[]
list - index
a = [2,4,6,4]
a.index(2)
0
a.index(4)
1
a.index(6)
2
a.index(8)
Traceback (most recent call last):
ValueError: 8 is not in list
list.clear() : Remove all items from list
list.index(value): Return first index of value.
Raises ValueError if the value
is not present.

17. a = [1,2,3,4,5,6]
b = ['a','b']
a = [0,1,2,3,4,5,6]
b = ['a','b']
a = b.copy()
a
['a', 'b']
a = [0, 1, 2, 3, 4, 5]
b = []
b = a.copy()
b = [0, 1, 2, 3, 4, 5]
list - copy
a = [0,1,2,3,4,5,6]
b = ['a','b']
a[3:] = b.copy()
a
[0, 1, 2, 'a', 'b']
a = [0,1,2,3,4,5,6]
b = ['a','b']
a[3:4] = b.copy()
a = [0, 1, 2, 'a', 'b', 4, 5, 6]
Example
Example
Example Example
list.copy(): A shallow copy of list to another list

18. list - extend
a = [0,1,2]
b = ['a','b','c']
b.extend(a)
b = ['a', 'b', 'c', 0, 1, 2]
b.extend(a)
b = ['a', 'b', 'c', 0, 1, 2, 0, 1, 2]
list.extend(iterable): extend list by appending elements from the iterable

19. list-count
a = [0,1,1,2,2,2]
a.count(0)
1
a.count(1)
2
a.count(2)
3
a.count(3)
0
a =['A','B','B','C','C','C']
a.count('A')
1
a.count('B')
2
a.count('C')
3
list.count(value): Return number of occurrences of value

20. list-pop
a = [0,1,2,3,4,5]
b = a.pop()
b = 5
a = [0, 1, 2, 3, 4]
a.pop()
a = [0,1,2,3]
c= a.pop()
c = 3
a = [0,1,2]
0 1 2 3 4
0 1 2 3 4
0 1 2 3
5
5
0 1 2 3
4
list.pop([index]): Remove and return item at index (default last).
Raises IndexError if list is empty or index is out of range.

21. list append and pop example
a = [2,4,6,8]
b = []
b.append(a.pop())
a =[2, 4, 6]
b =[8]
b.append(a.pop())
a = [2, 4]
b = [8, 6]
b.append(a.pop())
a = [2]
b =[8, 6, 4]
b.append(a.pop())
a = []
b = [8, 6, 4, 2]
2 4 6 8
2 4 6
2 4
2
8
8 6
8 6 4
8 6 4 2
Move the elements from list-a to list-b

22. list sort and reverse
a = [1,5,9,7,0,3,6,4,2,8]
a.reverse()
a = [8, 2, 4, 6, 3, 0, 7, 9, 5, 1]
a.sort()
a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
a.reverse()
a = [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
a = ['h','a','m','d','a','r','d']
a.sort()
a = ['a', 'a', 'd', 'd', 'h', 'm', 'r']
a.reverse()
a = ['r', 'm', 'h', 'd', 'd', 'a', 'a']
reverse(): Reverse the Array element
sort(): Place element in ascending order

23. list -remove
a = [1,2,2,3,3]
a.remove(1)
a = [2, 2, 3, 3]
a.remove(2)
a = [2, 3, 3]
a.remove(3)
a = [2, 3]
1 2 2 3 3
remove(value): Remove first occurrence of value.
Return ValueError if the value is not present.
1 2 2 3 3
2 2 3 3
2 3 3

24. list - insert
a = [0,1,2,3,4]
a.insert(2,5)
a = [0, 1, 5, 2, 3, 4]
a.insert(4,9)
a = [0, 1, 5, 2, 9, 3, 4]
a.insert(9,7)
a = [0, 1, 5, 2, 9, 3, 4, 7]
Insert( index position , value ): Insert object before index position
0 1 2 3 4
1 5 2 3 4
2 9 3 4 7
5 2 9 3 4
0
10
510
5
9
7

25. Exercise
• First generate 20 Random number
• Separate the Random number in two different
list that are
– Even[]
– Odd

26. Example Solution
import random
from random import randint
a = []
even = []
odd = []
for i in range(20):
a.append(randint(2,10))
print(a)
a.reverse()
print(a)
for i in range(20):
b = a.pop()
if(b%2 == 0):
even.append(b)
else:
odd.append(b)
print(even)
print(odd)
20 Random Number:
[8, 2, 4, 3, 4, 9, 4, 8, 8, 10, 9, 6, 3, 7, 7,
7, 3, 4, 4, 3]
Reverse the List:
[3, 4, 4, 3, 7, 7, 7, 3, 6, 9, 10, 8, 8, 4, 9,
4, 3, 4, 2, 8]
List of Even Number:
[8, 2, 4, 4, 4, 8, 8, 10, 6, 4, 4]
List of Odd Number:
[3, 9, 9, 3, 7, 7, 7, 3, 3]
Program

27. 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

28. Python Programming code comparison with C
programming code
Python program C/C++ program
Multi-line comments
Including library
Declaring variable
Multi-line statement
Code Block
Single-line statement
Single line comments
‘’’ The Python Language
Example code ’’’
Import time
a=10 #integer value
name = 'karachi' #String
for i in range (a):
print("Hamdard")
print('University')
print(name)
#program end
/* The C/C++ language
Example code */
#include <iostream>
using namespace std;
int main()
{
int a = 10;
char name[10] = "Karachi";
for(int i =0 ; i <a ; i ++ )
{
cout<<"Hamdard ";
cout<<"University"<<endl;
}
cout<<name;
return 0;
}
//program end

29. THANK YOU