Elif ladder execution in Python - Mini Project: Build & Apply

Elif Ladder Execution

📖 Scenario: You are creating a simple program to categorize a person's age group based on their age. This is useful in many real-life situations like ticket pricing, event access, or surveys.

🎯 Goal: Build a Python program that uses an elif ladder to print the correct age group for a given age.

📋 What You'll Learn

Create a variable called age with a specific integer value.

Create a variable called child_age_limit and set it to 12.

Use an if-elif-else ladder to check the age against child_age_limit and other age ranges.

Print the correct age group as a string: 'Child', 'Teenager', 'Adult', or 'Senior'.

💡 Why This Matters

🌍 Real World

Age group classification is used in ticket pricing, content restrictions, and marketing to target the right audience.

💼 Career

Understanding conditional statements like <code>elif</code> ladders is fundamental for programming jobs that involve decision-making logic.

1

Set the age variable

Create a variable called age and set it to 20.

Python

# Create a variable called age and set it to 20
# Your code here

Hint

Use the assignment operator = to set the value.

2

Set the child age limit

Create a variable called child_age_limit and set it to 12.

Python

age = 20
# Create a variable called child_age_limit and set it to 12
# Your code here

Hint

This variable will help us decide if someone is a child or older.

3

Write the elif ladder to check age groups

Write an if-elif-else ladder using the variables age and child_age_limit to print:
- 'Child' if age is less than or equal to child_age_limit
- 'Teenager' if age is between 13 and 19 inclusive
- 'Adult' if age is between 20 and 64 inclusive
- 'Senior' if age is 65 or older

Python

age = 20
child_age_limit = 12
# Write the if-elif-else ladder to check age groups
# Your code here

Hint

Use comparison operators like <= and logical operators like and or chained comparisons.

4

Run the program to see the output

Run the program and observe the printed output for the given age.

Python

age = 20
child_age_limit = 12
if age <= child_age_limit:
    print('Child')
elif 13 <= age <= 19:
    print('Teenager')
elif 20 <= age <= 64:
    print('Adult')
else:
    print('Senior')
# Run the program to see the output

Hint

The program should print the correct age group based on the value of age.

Practice

1.

What does an elif ladder do in Python?

easy

A. Only checks the last condition in the ladder

B. Runs all conditions regardless of their truth value

C. Checks multiple conditions in order and runs the first true block

D. Skips all conditions and runs the else block always

Solution

1. Step 1: Understand the purpose of elif ladder

   An elif ladder checks conditions one by one in order.

2. Step 2: Identify behavior on true condition

   It stops checking further once it finds the first true condition and runs that block.

3. Final Answer:

   Checks multiple conditions in order and runs the first true block -> Option C

4. Quick Check:

   Elif ladder = first true condition runs [OK]

Hint: Elif stops at first true condition found [OK]

Common Mistakes:

• Thinking all conditions run
• Believing else runs before elif
• Assuming elif checks last only

2.

Which of these is the correct syntax for an elif statement in Python?

if x > 10:
    print("Big")
____ x > 5:
    print("Medium")
else:
    print("Small")

easy

A. elif

B. else if

C. elseif

D. elif:

Solution

1. Step 1: Recall Python elif syntax

   Python uses 'elif' without spaces or colon after it.

2. Step 2: Check options for correct keyword

   Only 'elif' is correct; 'else if' and 'elseif' are invalid in Python.

3. Final Answer:

   elif -> Option A

4. Quick Check:

   Python elif keyword = elif [OK]

Hint: Use 'elif' exactly, no spaces or colon after it [OK]

Common Mistakes:

• Writing 'else if' like other languages
• Adding colon after elif keyword
• Using 'elseif' as one word

3.

What will be the output of this code?

score = 75
if score >= 90:
    print("A")
elif score >= 80:
    print("B")
elif score >= 70:
    print("C")
else:
    print("F")

medium

A. A

B. B

C. F

D. C

Solution

1. Step 1: Check conditions in order with score=75

   score >= 90? No. score >= 80? No. score >= 70? Yes.

2. Step 2: Print output for first true condition

   Prints "C" and stops checking further.

3. Final Answer:

   C -> Option D

4. Quick Check:

   75 >= 70 = True, prints C [OK]

Hint: Check conditions top to bottom, stop at first true [OK]

Common Mistakes:

• Choosing B or A ignoring order
• Thinking else runs when elif true
• Confusing >= with >

4.

Find the error in this elif ladder code:

num = 10
if num < 5:
    print("Small")
elif num > 5
    print("Big")
else:
    print("Medium")

medium

A. Missing colon after elif condition

B. Wrong indentation of print statements

C. Using else without condition

D. Using < instead of > in if

Solution

1. Step 1: Check syntax of elif line

   Line 'elif num > 5' is missing a colon at the end.

2. Step 2: Identify correct syntax for elif

   Elif condition must end with a colon ':' to be valid.

3. Final Answer:

   Missing colon after elif condition -> Option A

4. Quick Check:

   Elif line needs colon ':' [OK]

Hint: Always put colon after if/elif/else lines [OK]

Common Mistakes:

• Forgetting colon after elif
• Misaligning indentation
• Thinking else needs condition

5.

Given this code, what will be printed if value = 0?

value = 0
if value:
    print("True")
elif value == 0:
    print("Zero")
else:
    print("False")

hard

A. True

B. Zero

C. False

D. No output

Solution

1. Step 1: Evaluate if condition with value=0

   In Python, 0 is treated as False, so 'if value:' is False.

2. Step 2: Check elif condition

   'elif value == 0:' is True, so it prints "Zero" and stops.

3. Final Answer:

   Zero -> Option B

4. Quick Check:

   0 is falsy, elif value==0 True [OK]

Hint: Remember 0 is False, check explicit elif next [OK]

Common Mistakes:

• Thinking if value: is True for 0
• Ignoring elif condition
• Assuming else runs always