Lecture on Fundamentals of Python Programming-2

Prof Dr. Iqbal Ahmed
Dept. of Computer Science and Engineering

Python: If Statement
a = 33
b = 200
if b > a:
print("b is greater than
a")
If statement, without indentation (will raise an error)

Python: elif Statement
a = 33
b = 33
if b > a:
print("b is greater than
a")
elif a == b:
print("a and b are equal")
The elif keyword is Python's way of saying
"if the previous conditions were not true,
then try this condition".
The else keyword catches anything which
isn't caught by the preceding conditions
a = 200
b = 33
if b > a:
print("b is greater than a")
elif a == b:
print("a and b are equal")
else:
print("a is greater than b")
If you have only one statement to execute,
you can put it on the same line as the if
statement: Short Hand of If
if a > b: print("a is greater than
b")
a = 2
b = 330
print("A") if a >

Python: if Statement
a = 200
b = 33
c = 500
if a > b and c > a:
print("Both conditions are
True")
AND operation
OR operation
a = 200
b = 33
c = 500
if a > b or a > c:
print("At least one of the
conditions is True")
NOT operation
a = 33
b = 200
if not a > b:
print("a is NOT greater than
b")

Python: Nested If Statement
x = 41
if x > 10:
print("Above ten,")
if x > 20:
print("and also above
20!")
else:
print("but not above
20.")
if statements cannot be empty, but if you for
some reason have an if statement with no
content, put in the pass statement to avoid
getting an error
a = 33
b = 200
if b > a:
pass
You can have if statements inside if statements,
this is called nested if statements.

Python: Match Statement
day = 4
match day:
case 1:
print("Monday")
case 2:
print("Tuesday")
case 3:
print("Wednesday")
case 4:
print("Thursday")
case 5:
print("Friday")
case 6:
print("Saturday")
case 7:
print("Sunday")
This is how it works:
•The match expression is evaluated once.
•The value of the expression is compared with
the values of each case.
•If there is a match, the associated block of code
is executed.
Instead of writing many if..else statements, you
can use the match statement.
The match statement selects one of many code
blocks to be executed.
match expression:
case x:
code block
case y:
code block
case z:
code block

day = 4
match day:
case 6:
print("Today is
Saturday")
case 7:
print("Today is Sunday")
case _:
print("Looking forward to
the Weekend")
Use the pipe character | as an or operator in
the case evaluation to check for more than one
value match in one case
Use the underscore character _ as the last case
value if you want a code block to execute when
there are not other matches
day = 4
match day:
case 1 | 2 | 3 | 4 | 5:
print("Today is a
weekday")
case 6 | 7:
print("I love weekends!")

month = 5
day = 4
match day:
case 1 | 2 | 3 | 4 | 5 if month == 4:
print("A weekday in April")
case 1 | 2 | 3 | 4 | 5 if month == 5:
print("A weekday in May")
case _:
print("No match")
You can add if statements in the case evaluation
as an extra condition-check:
The value _ will always match, so it is important to place it as the last case to make
it behave as a default case.

Python Loops
i = 1
while i < 6:
print(i)
i += 1
With the while loop we can execute a
set of statements as long as a condition
is true.
Python has two primitive loop
commands:
•while loops
•for loops
Note: remember to increment i, or else the loop will continue forever.

Break Statement
i = 0
while i < 6:
i += 1
if i == 3:
continue
print(i)
With the continue statement we can
stop the current iteration, and
continue with the next:
With the break statement we can
stop the loop even if the while
condition is true:
i = 1
while i < 6:
print(i)
if i == 3:
break
i += 1
With the else statement we can run
a block of code once when the
condition no longer is true:
i = 1
while i < 6:
print(i)
i += 1
else:
print("i is no longer less than

Python For loops
fruits =
["apple", "banana", "cherry"]
for x in fruits:
print(x)
if x == "banana":
break
A for loop is used for iterating over a
sequence (that is either a list, a tuple,
a dictionary, a set, or a string).
With the for loop we can execute a
set of statements, once for each item
in a list, tuple, set etc
fruits =
for x in fruits:
print(x)
With the break statement we can stop
the loop before it has looped through
all the items:
fruits =
for x in fruits:
if x == "banana":
break

Python For loops
for x in range(6):
print(x)
for x in range(2, 6):
print(x)
for x in range(2, 30, 3):
print(x)
With the continue statement we can
stop the current iteration of the loop,
and continue with the next:
fruits =
for x in fruits:
if x == "banana":
continue
print(x)
To loop through a set of code a specified
number of times, we can use
the range() function.
Note that range(6) is not the values of 0
to 6, but the values 0 to 5.
it is possible to specify the starting value
by adding a parameter: range(2, 6),
which means values from 2 to 6 (but not
including 6):
it is possible to specify the increment value by
adding a third parameter: range(2, 30, 3)

Python For loops
The else keyword in a for loop specifies
a block of code to be executed when
the loop is finished.
for x in range(6):
print(x)
else:
print("Finally finished!")
for x in range(6):
if x == 3: break
print(x)
else:
print("Finally finished!")
A nested loop is a loop inside a loop.
The "inner loop" will be executed one
time for each iteration of the "outer
loop”.
adj = ["red", "big", "tasty"]
fruits =
for x in adj:
for y in fruits:
print(x, y)

Python For loops
for loops cannot be empty, but if you
for some reason have a for loop with
no content, put in the pass statement
to avoid getting an error.
for x in [0, 1, 2]:
pass

1. Grading System (if, elif, nested if)
Write a program that:
•Asks the user for a marks input (0 to 100).
•Based on the marks, print the grade:
• 90-100 → A+
• 80-89 → A
• 70-79 → B
• 60-69 → C
• 50-59 → D
• Below 50 → Fail
•Tricky part: If marks are exactly 100, print "Perfect Score!" in addition to
grade.
Solve some real problem!

2. Food Menu Selection (match)
•Displays a menu:
1. Pizza
2. Burger
3. Pasta
4. Salad
•Takes user's choice (1-4).
•Use a match-case to print a different message for each food item.
•Tricky part: If they input something else, print "Invalid choice. Try again!"

3. Guess the Secret Number (while loop with break/continue)
•A secret number (say 7) is fixed.
•The user is asked to guess the number.
•If guess is correct, print "Congratulations!" and break the loop.
•If guess is wrong:
• If the guess is negative, continue without any message.
• Else print "Wrong! Try again."
4. Multiplication Table (for loop)
•Asks the user for a number.
•Print its multiplication table from 1 to 10 using a for loop.
•Tricky part: If the number is negative, print "Tables not available for negative
numbers." and stop.

5. Number Triangle (nested for loop)
•Asks the user for a number (e.g., 5).
•Print a number triangle like this:
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
Use nested for loops: Outer loop for rows, inner loop for numbers in
the row.

6. Odd or Even Game (nested if with while loop)
•Keeps asking the user for a number until they enter 0.
•For each number:
• Check if it is even or odd.
• Then check:
• If even and greater than 50, print "Big even number!"
• If odd and less than 10, print "Tiny odd number!"
• Otherwise, just print "Even" or "Odd" normally.

7. Match a Month (match-case + nested if)
•Asks the user for a month number (1-12).
•Use a match-case to:
• Print the month's name (e.g., 1 → January).
•Then inside the matched case, using nested if, check:
• If the month is January, print "Happy New Year!"
• If the month is December, print "Merry Christmas!"

marks = int(input("Enter your marks (0-100): "))
if marks < 0 or marks > 100:
print("Invalid marks entered.")
else:
if marks == 100:
print("Perfect Score!")
if marks >= 90:
print("Grade: A+")
elif marks >= 80:
print("Grade: A")
elif marks >= 70:
print("Grade: B")
elif marks >= 60:
print("Grade: C")
elif marks >= 50:
print("Grade: D")
else:
print("Grade: Fail")
1. Solutions!!

choice = int(input("Choose an item (1-4):n1. Pizzan2. Burgern3. Pastan4. Saladn"))
match choice:
case 1:
print("You selected Pizza! Yummy!")
case 2:
print("Burger selected. Enjoy your meal!")
case 3:
print("Pasta it is! Bon appétit!")
case 4:
print("Healthy choice! Salad selected.")
case _:
print("Invalid choice. Try again!")
2. Solutions!!

secret_number = 7
while True:
guess = int(input("Guess the secret number: "))
if guess < 0:
continue # Skip negative guesses silently
if guess == secret_number:
print("Congratulations! You guessed it right!")
break
else:
print("Wrong! Try again.")
3 & 4. Solutions!!
num = int(input("Enter a number for multiplication table: "))
if num < 0:
print("Tables not available for negative numbers.")
else:
for i in range(1, 11):
print(f"{num} x {i} = {num * i}")

rows = int(input("Enter number of rows for the
triangle: "))
for i in range(1, rows + 1):
for j in range(1, i + 1):
print(j, end=" ")
print() # Newline after each row
while True:
number = int(input("Enter a number (0 to quit): "))
if number == 0:
print("Goodbye!")
break
if number % 2 == 0:
if number > 50:
print("Big even number!")
else:
print("Even")
else:
if number < 10:
print("Tiny odd number!")
else:
print("Odd")
5 & 6.
Solutions!!

month = int(input("Enter month number (1-12): "))
match month:
case 1:
print("January")
if month == 1:
print("Happy New Year!")
case 2:
print("February")
case 3:
print("March")
case 4:
print("April")
case 5:
print("May")
case 6:
print("June")
7. Solutions
case 7:
print("July")
case 8:
print("August")
case 9:
print("September")
case 10:
print("October")
case 11:
print("November")
case 12:
print("December")
if month == 12:
print("Merry Christmas!")
case _:
print("Invalid month number.")

Lecture on Fundamentals of Python Programming-2

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