📘 Lesson 5 examples: Conditional Statements

🔹 1. What are Conditional Statements?

Conditional statements allow a program to make decisions.

👉 Python checks a condition
👉 If it is True, one block runs
👉 If it is False, another block runs

Python uses:

• if
• elif
• else

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🔹 2. Basic if Statement

Example 1: Simple Condition

age = 20

if age >= 18:
    print("Eligible to vote")

Output

Eligible to vote

📌 Explanation

• Condition: age >= 18
• Result is True
• Code inside if runs
• Indentation is mandatory

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🔹 3. if Condition Fails

age = 15

if age >= 18:
    print("Eligible to vote")

Output

(no output)

📌 Explanation

• Condition is False
• Python skips the if block

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🔹 4. if – else Statement

Example 2: Voting Eligibility

age = 16

if age >= 18:
    print("Eligible to vote")
else:
    print("Not eligible to vote")

Output

Not eligible to vote

📌 Explanation

• If condition is True → if runs
• If condition is False → else runs

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🔹 5. if – elif – else Statement

Used when there are multiple conditions.

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Example 3: Student Grade System

marks = 82

if marks >= 90:
    print("Grade A")
elif marks >= 75:
    print("Grade B")
elif marks >= 60:
    print("Grade C")
else:
    print("Fail")

Output

Grade B

📌 Explanation

• Python checks conditions top to bottom
• First True condition runs
• Remaining conditions are skipped

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🔹 6. Conditions Using Logical Operators

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Example 4: Admission Eligibility

age = 20
has_id = True

if age >= 18 and has_id:
    print("Admission allowed")
else:
    print("Admission denied")

Output

Admission allowed

📌 Explanation

• and → both conditions must be true

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Example 5: Scholarship Eligibility

marks = 85
income = 20000

if marks >= 80 or income <= 25000:
    print("Eligible for scholarship")
else:
    print("Not eligible")

Output

Eligible for scholarship

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🔹 7. Nested if (if inside if)

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Example 6: Login System

username = "Sameer"
password = "1234"

if username == "Sameer":
    if password == "1234":
        print("Login successful")
    else:
        print("Wrong password")
else:
    print("Wrong username")

Output

Login successful

📌 Explanation

• Inner if runs only if outer if is true

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🔹 8. if with User Input (VERY IMPORTANT)

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Example 7: Even or Odd Number

number = int(input("Enter a number: "))

if number % 2 == 0:
    print("Even number")
else:
    print("Odd number")

Sample Output

Enter a number: 7
Odd number

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🔹 9. Real-Life Example: Salary Bonus

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Example 8

salary = float(input("Enter salary: "))

if salary >= 30000:
    bonus = 5000
else:
    bonus = 2000

print("Bonus:", bonus)

Sample Output

Enter salary: 28000
Bonus: 2000

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🔹 10. Comparison of Strings

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Example 9

name = "Ayesha"

if name == "Ayesha":
    print("Welcome Ayesha")
else:
    print("Unknown user")

Output

Welcome Ayesha

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🔹 11. Multiple Conditions Practice

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Example 10: Age Group

age = 65

if age < 13:
    print("Child")
elif age < 20:
    print("Teenager")
elif age < 60:
    print("Adult")
else:
    print("Senior Citizen")

Output

Senior Citizen

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🔹 12. Common Mistakes (IMPORTANT)

❌ Missing indentation
❌ Using = instead of ==
❌ Forgetting type casting for input
❌ Wrong condition order

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🧠 Final Summary

✔ if checks condition
✔ else runs when condition fails
✔ elif handles multiple conditions
✔ Python uses indentation instead of brackets
✔ Conditions return True or Falsehen condition fails
✔ elif handles multiple conditions
✔ Python uses indentation instead of brackets
✔ Conditions return True or False