Conditions in Python -1

Relational, Logical, and Conditional Operators in Python

Understand how Python makes decisions with comparisons, logical connectors, and conditional statements.

1) Relational Operators

x, y = 10, 20
print(x == y)   # False
print(x != y)   # True
print(x > y)    # False
print(x < y)    # True
print(x >= 10)  # True
print(y <= 15)  # False

2) Logical Operators

a, b = 5, 15
print(a > 0 and b > 0)   # True
print(a > 0 or b < 0)    # True
print(not(a > b))        # True

3) if, else, and elif

marks = 72
if marks >= 90:
    print("Grade A")
elif marks >= 75:
    print("Grade B")
elif marks >= 50:
    print("Grade C")
else:
    print("Fail")
# Output: Grade B

4) Ternary Operator

Shorthand: x if condition else y.

age = 18
status = "Adult" if age >= 18 else "Minor"
print(status)  # Adult

# Example: maximum of two numbers
x, y = 25, 40
maximum = x if x > y else y
print(maximum)  # 40

5) Multilevel Conditions

x, y, z = 15, 40, 30
# Find maximum of three numbers using nested if-else
if x > y and x > z:
    maximum = x
elif y > z:
    maximum = y
else:
    maximum = z
print(maximum)  # 40

6) Practical Examples

Leap Year

year = 2024
if (year % 400 == 0) or (year % 4 == 0 and year % 100 != 0):
    print("Leap Year")   # Leap Year
else:
    print("Not a Leap Year")

Triangle Possibility and Type

a, b, c = 5, 5, 8
if a + b > c and a + c > b and b + c > a:
    if a == b == c:
        print("Equilateral Triangle")
    elif a == b or b == c or a == c:
        print("Isosceles Triangle")  # Isosceles Triangle
    else:
        print("Scalene Triangle")
else:
    print("Triangle not possible")

Convert 24-Hour Time to AM/PM

hour = 21
minute = 15

if hour == 0:
    print(f"12:{minute} AM")
elif hour < 12:
    print(f"{hour}:{minute} AM")
elif hour == 12:
    print(f"12:{minute} PM")
else:
    print(f"{hour - 12}:{minute} PM")  # 9:15 PM

7) Assignments (Click to Show Answer)

Q1: Write a ternary operator to find the smallest of two numbers.

a, b = 8, 3
minimum = a if a < b else b
print(minimum)  # 3

Q2: Write a program to check whether a year is a leap year.

year = 1900
if (year % 400 == 0) or (year % 4 == 0 and year % 100 != 0):
    print("Leap Year")
else:
    print("Not Leap Year")  # Not Leap Year

Q3: Given three sides, decide if a triangle is possible. If possible, classify it.

a, b, c = 7, 7, 7
# Output: Equilateral Triangle

Q4: Convert 14:45 (24-hour format) to AM/PM.

hour, minute = 14, 45
print(f"{hour-12}:{minute} PM")  # 2:45 PM

© Champak Roy • Python Lesson on Relational, Logical, and Conditional Operators