Mastering Conditional Logic in Python: If-Else Statements and Match-Case Explained

If-Else Conditional Statements in Python

The if-else statement is used to perform actions based on conditions.

---

Syntax:

if condition:
    # Code to execute if the condition is True
else:
    # Code to execute if the condition is False

---

Examples:

1. Basic If-Else Example:

age = 18
if age >= 18:
    print("You are eligible to vote.")
else:
    print("You are not eligible to vote.")

2. Using Multiple Conditions (If-Elif-Else):

marks = 85
if marks >= 90:
    print("Grade: A")
elif marks >= 75:
    print("Grade: B")
else:
    print("Grade: C")

3. Nested If-Else:

marks = 85

if marks >= 90:
    print("Grade: A")
elif marks >= 75:
    if marks >= 80:
        print("Grade: B+")
    else:
        print("Grade: B")
elif marks >= 50:
    if marks >= 60:
        print("Grade: C+")
    else:
        print("Grade: C")
else:
    print("Grade: F")

---

Key Points:

• Indentation is mandatory for defining blocks of code.

• Use elif for multiple conditions.

• else is optional and runs only if all conditions are False.

---

Practice:

if -else :

if - elif - else :

Nested if -else:

Make a Python program that uses the if-elif-else loop to wish the user based on the current time:

import datetime
ghanta = datetime.datetime.now().hour

if(5 <= ghanta < 12):
  print("Good Morning Safia")

elif(12 <= ghanta < 17):
 print("Good Afternoon Safia")

elif(17 <= ghanta < 21):
  print("Good Evening Safia")

else:
  print("SO jA Safia Good Night")

match-case Statement in Python :

The match-case statement is a feature introduced in Python 3.10. It works like a switch-case in other programming languages. It allows us to match values against specific patterns and execute code based on the match.

match variable:
    case pattern1:
        # Code for pattern1
    case pattern2:
        # Code for pattern2
    case _:
        # Default case (like else)

safia = input("Enter the Operation(Add,Sub,Mul,Div): ")

match safia:
 case "add":
  print("Add two numbers: ", 5 + 2)
 case "sub":
  print("Sub two numbers: ", 5 - 3)
 case "mul":
   print("Mul two numbers: ", 5 * 3)
 case "div":
   print("Div two numbers: ", 5/3 )
 case "_":
   print("Invalid Operations")

Step-by-Step Explanation

1. safia : Takes user input for the operation (e.g., add, sub, etc.).

2. match safia: Matches the value of the safia variable.

3. case Statements:

   • case "add": Executes if the input is "add".

   • case _: Acts as the default case if no other match is found.

4. The program performs calculations and prints the result.

Another Example: Weekday Matcher

day = int(input("Enter a number (1-7): "))

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")
    case _:
        print("Invalid day number!")

---

Why Use match-case?

• Cleaner and more readable than multiple if-elif-else blocks.

• Great for matching exact values or patterns.

• Introduced in Python 3.10 for better pattern matching.

  we can write the same logic using if-elif-else instead of match-case :

• Example: Weekday Matcher Using if-elif-else

    day = int(input("Enter a number (1-7): "))  # Take input for day number
  
    # Match the day using if-elif-else
    if day == 1:
        print("Monday")
    elif day == 2:
        print("Tuesday")
    elif day == 3:
        print("Wednesday")
    elif day == 4:
        print("Thursday")
    elif day == 5:
        print("Friday")
    elif day == 6:
        print("Saturday")
    elif day == 7:
        print("Sunday")
    else:
        print("Invalid day number!")  # Default case for invalid input
  

  ---