Elseif ladder execution in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the number is positive.

PHP

<?php
$number = 10;
if ($number [1] 0) {
    echo "Positive number";
}
?>

Drag options to blanks, or click blank then click option'

A<

B>

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' will check for negative numbers.

Using '==' checks only if number equals zero.

The condition $number > 0 checks if the number is positive.

2fill in blank

medium

Complete the elseif condition to check if the number is zero.

PHP

<?php
$number = 0;
if ($number > 0) {
    echo "Positive number";
} elseif ($number [1] 0) {
    echo "Zero";
}
?>

Drag options to blanks, or click blank then click option'

A==

B<

C>

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' checks if number is not zero, which is incorrect here.

Using '<' or '>' checks for negative or positive numbers, not zero.

The condition $number == 0 checks if the number is exactly zero.

3fill in blank

hard

Fix the error in the elseif condition to check if the number is negative.

PHP

<?php
$number = -5;
if ($number > 0) {
    echo "Positive number";
} elseif ($number [1] 0) {
    echo "Negative number";
}
?>

Drag options to blanks, or click blank then click option'

A>

B!=

C==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' checks for positive numbers, not negative.

Using '==' checks if number equals zero, not negative.

The condition $number < 0 checks if the number is negative.

4fill in blank

hard

Fill both blanks to complete the elseif ladder that prints the correct message based on the number.

PHP

<?php
$number = 0;
if ($number [1] 0) {
    echo "Positive number";
} elseif ($number [2] 0) {
    echo "Negative number";
} else {
    echo "Zero";
}
?>

Drag options to blanks, or click blank then click option'

A>

B<

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the operators will cause wrong messages.

Using '==' in the first two conditions misses positive or negative checks.

The first condition checks if the number is greater than zero (positive). The elseif checks if it is less than zero (negative). Otherwise, it is zero.

5fill in blank

hard

Fill all three blanks to create an elseif ladder that prints the correct message for positive, negative, or zero values.

PHP

<?php
$number = -3;
if ($number [1] 0) {
    echo "Positive number";
} elseif ($number [2] 0) {
    echo "Negative number";
} elseif ($number [3] 0) {
    echo "Zero";
}
?>

Drag options to blanks, or click blank then click option'

A>

B<

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' instead of '==' for zero check causes wrong output.

Mixing up the operators leads to incorrect messages.

The ladder checks if the number is greater than zero (positive), less than zero (negative), or equal to zero (zero).

Practice

1.

What does an elseif ladder do in PHP?

easy

A. It only checks the last condition in the ladder.

B. It runs all conditions regardless of their truth value.

C. It checks conditions one by one and runs the first true block.

D. It skips all conditions and runs the else block always.

Solution

1. Step 1: Understand elseif ladder behavior

   An elseif ladder evaluates conditions from top to bottom.

2. Step 2: Identify execution flow

   It executes the code block of the first condition that is true and skips the rest.

3. Final Answer:

   It checks conditions one by one and runs the first true block. -> Option C

4. Quick Check:

   Elseif ladder = first true condition runs [OK]

Hint: Runs only first true condition block in order [OK]

Common Mistakes:

• Thinking all conditions run
• Believing it checks only last condition
• Assuming else always runs

2.

Which of the following is the correct syntax for an elseif ladder in PHP?

<?php
if (condition1) {
    // code
} elseif (condition2) {
    // code
} else {
    // code
}
?>

easy

A. if (condition1) {} elseif (condition2) {} else {}

B. if (condition1) {} else if (condition2) {} else {}

C. if (condition1) {} elseif condition2 {} else {}

D. if condition1 {} elseif (condition2) {} else {}

Solution

1. Step 1: Check PHP elseif syntax

   PHP uses elseif (condition) with parentheses and no space between else and if.

2. Step 2: Compare options

   if (condition1) {} elseif (condition2) {} else {} matches correct syntax; others have syntax errors like missing parentheses or wrong spacing.

3. Final Answer:

   if (condition1) {} elseif (condition2) {} else {} -> Option A

4. Quick Check:

   Correct elseif syntax = if (condition1) {} elseif (condition2) {} else {} [OK]

Hint: Use 'elseif' as one word with parentheses [OK]

Common Mistakes:

• Writing 'else if' as two words in PHP
• Omitting parentheses around conditions
• Missing curly braces

3.

What will be the output of this PHP code?

<?php
$score = 75;
if ($score >= 90) {
    echo "Grade A";
} elseif ($score >= 80) {
    echo "Grade B";
} elseif ($score >= 70) {
    echo "Grade C";
} else {
    echo "Grade F";
}
?>

medium

A. Grade A

B. Grade F

C. Grade B

D. Grade C

Solution

1. Step 1: Check conditions in order

   Score is 75. First condition (>=90) is false, second (>=80) false, third (>=70) true.

2. Step 2: Determine executed block

   Since third condition is true, it prints "Grade C" and skips else.

3. Final Answer:

   Grade C -> Option D

4. Quick Check:

   75 >= 70 = Grade C [OK]

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

Common Mistakes:

• Choosing Grade B or A incorrectly
• Ignoring elseif order
• Assuming else runs always

4.

Find the error in this PHP code snippet:

<?php
$age = 20;
if ($age > 18) {
    echo "Adult";
} elseif $age >= 13 {
    echo "Teenager";
} else {
    echo "Child";
}
?>

medium

A. Missing parentheses around elseif condition

B. Missing semicolon after echo statements

C. Incorrect variable name in elseif

D. No else block present

Solution

1. Step 1: Review elseif syntax

   In PHP, conditions must be inside parentheses, but here elseif lacks parentheses.

2. Step 2: Check other parts

   Echo statements have semicolons, variable names are correct, else block exists.

3. Final Answer:

   Missing parentheses around elseif condition -> Option A

4. Quick Check:

   Parentheses required for elseif condition [OK]

Hint: Always put conditions in parentheses [OK]

Common Mistakes:

• Forgetting parentheses in elseif
• Confusing semicolon placement
• Assuming else block is optional

5.

You want to assign a category based on age using an elseif ladder. Which code correctly assigns "Child" for age < 13, "Teen" for age between 13 and 19 inclusive, and "Adult" for age 20 or more?

<?php
$age = 15;
if ($age < 13) {
    $category = "Child";
} elseif ($age >= 13 && $age <= 19) {
    $category = "Teen";
} else {
    $category = "Adult";
}
echo $category;
?>

hard

A. Syntax error due to missing elseif keyword

B. Correctly assigns categories as required

C. Assigns "Adult" for age 19 incorrectly

D. Assigns "Child" for age 13 incorrectly

Solution

1. Step 1: Check age ranges in conditions

   First condition covers age less than 13, second covers 13 to 19 inclusive, else covers 20 or more.

2. Step 2: Verify assignment and output

   Each category is assigned correctly based on age, and echo prints the category.

3. Final Answer:

   Correctly assigns categories as required -> Option B

4. Quick Check:

   Age ranges match categories perfectly [OK]

Hint: Use && to combine conditions in elseif [OK]

Common Mistakes:

• Overlapping or missing age ranges
• Using else if instead of elseif in PHP
• Forgetting to echo the category