Break statement with levels in PHP - Mini Project: Build & Apply

Break Statement with Levels in PHP

📖 Scenario: Imagine you are managing a small library system. You want to check shelves and books to find a specific book. Once found, you want to stop checking further shelves and books immediately.

🎯 Goal: You will create nested loops to simulate shelves and books. Then, you will use the break statement with levels to stop the loops once the book is found.

📋 What You'll Learn

Create two nested for loops: outer loop for shelves (1 to 3), inner loop for books (1 to 5).

Create a variable targetBook with the value 3 to represent the book to find.

Use break 2; to exit both loops when the target book is found.

Print a message showing which shelf and book was found.

💡 Why This Matters

🌍 Real World

Nested loops and breaking out of them are common when searching through multi-level data like shelves and books, menus and submenus, or rows and columns.

💼 Career

Understanding how to control loops with break levels helps in writing efficient code for data processing, web scraping, and game development.

1

Create nested loops for shelves and books

Create a for loop with variable $shelf from 1 to 3 and inside it create another for loop with variable $book from 1 to 5.

PHP

<?php
for ($shelf = 1; $shelf <= 3; $shelf++) {
    for ($book = 1; $book <= 5; $book++) {
        // Your code here
    }
}

Hint

Use two for loops, one inside the other, with the variables $shelf and $book.

2

Add a target book variable

Create a variable called $targetBook and set it to 3 before the loops.

PHP

<?php
$targetBook = 3;
for ($shelf = 1; $shelf <= 3; $shelf++) {
    for ($book = 1; $book <= 5; $book++) {
        // Your code here
    }
}

Hint

Define $targetBook before the loops to know which book to find.

3

Use break with levels to stop loops when book is found

Inside the inner loop, add an if statement to check if $book equals $targetBook. If yes, use break 2; to exit both loops.

PHP

<?php
$targetBook = 3;
for ($shelf = 1; $shelf <= 3; $shelf++) {
    for ($book = 1; $book <= 5; $book++) {
        if ($book == $targetBook) {
            // Your code here
        }
    }
}

Hint

Use break 2; to stop both loops when the target book is found.

4

Print the shelf and book found

After the loops, write a print statement to display: "Found book $targetBook on shelf $shelf".

PHP

<?php
$targetBook = 3;
for ($shelf = 1; $shelf <= 3; $shelf++) {
    for ($book = 1; $book <= 5; $book++) {
        if ($book == $targetBook) {
            break 2;
        }
    }
}
// Your code here

Hint

Use print to show the message with the variables $targetBook and $shelf.

Practice

1.

What does the break statement do in PHP loops?

easy

A. It skips the current iteration and continues the loop.

B. It pauses the loop until a condition is met.

C. It restarts the loop from the beginning.

D. It stops the current loop immediately.

Solution

1. Step 1: Understand the purpose of break

   The break statement is used to exit a loop early when a condition is met.

2. Step 2: Compare options

   The description "It stops the current loop immediately." correctly describes break. "It skips the current iteration..." describes continue. Restarting or pausing are incorrect.

3. Final Answer:

   It stops the current loop immediately. -> Option D

4. Quick Check:

   break stops loop [OK]

Hint: Break stops loops immediately, no more iterations [OK]

Common Mistakes:

• Confusing break with continue
• Thinking break pauses instead of stops
• Assuming break restarts the loop

2.

Which of the following is the correct syntax to break out of 2 nested loops in PHP?

for (...) {
    for (...) {
        // break here
    }
}

easy

A. break;

B. break(2);

C. break 2;

D. break 1;

Solution

1. Step 1: Recall break syntax with levels

   To exit multiple nested loops, PHP uses break n; where n is the number of loops to break out of.

2. Step 2: Identify correct syntax

   break 2; correctly breaks out of 2 loops. break(2); is invalid syntax. A plain break; or break 1; breaks only one loop.

3. Final Answer:

   break 2; -> Option C

4. Quick Check:

   break 2; exits 2 loops [OK]

Hint: Use break n; to exit n nested loops in PHP [OK]

Common Mistakes:

• Using break(2) which is invalid syntax
• Forgetting to specify number for multiple loops
• Using break 1; when 2 loops need exit

3.

What is the output of this PHP code?

$count = 0;
for ($i = 0; $i < 3; $i++) {
    for ($j = 0; $j < 3; $j++) {
        $count++;
        if ($i + $j == 2) {
            break 2;
        }
    }
}
echo $count;

medium

A. 5

B. 3

C. 4

D. 6

Solution

1. Step 1: Trace nested loops and break condition

   Loops run with i and j from 0 to 2. The break triggers when i + j == 2, breaking out of both loops immediately. count++ occurs before the check.

2. Step 2: Simulate iterations

   - i=0,j=0: count=1 (sum=0 !=2)
   - i=0,j=1: count=2 (sum=1 !=2)
   - i=0,j=2: count=3 (sum=2 ==2), break 2; loops stop
   Total count = 3.

3. Final Answer:

   3 -> Option B

4. Quick Check:

   3 increments before break 2 exits both loops [OK]

Hint: Count increments before break; break n exits n loops [OK]

Common Mistakes:

• Counting increments after break condition
• Ignoring break level effect
• Assuming break only exits inner loop

4.

Find the error in this PHP code snippet:

for ($i = 0; $i < 3; $i++) {
    for ($j = 0; $j < 3; $j++) {
        if ($i == $j) {
            break 3;
        }
        echo "$i,$j\n";
    }
}

medium

A. break 3; is invalid because only 2 loops exist.

B. break 3; should be break 2; to exit both loops.

C. break 3; causes infinite loop.

D. No error, code runs fine.

Solution

1. Step 1: Count nested loops

   There are 2 nested loops: outer and inner.

2. Step 2: Check break level usage

   Using break 3; tries to break out of 3 loops, but only 2 exist, causing a fatal error.

3. Final Answer:

   break 3; is invalid because only 2 loops exist. -> Option A

4. Quick Check:

   break n must be ≤ nested loops count [OK]

Hint: Break level cannot exceed nested loops count [OK]

Common Mistakes:

• Using break level higher than loops
• Assuming break 3 exits 2 loops
• Ignoring PHP fatal error on invalid break level

5.

You want to stop processing nested loops early when a condition is met, but only exit the inner loop sometimes and both loops other times. Which code snippet correctly uses break with levels?

for ($i = 0; $i < 5; $i++) {
    for ($j = 0; $j < 5; $j++) {
        if ($i == 2 && $j == 3) {
            break 2; // exit both loops
        } elseif ($j == 4) {
            break; // exit inner loop only
        }
        echo "$i,$j\n";
    }
}

hard

A. Correct use of break with levels to control loop exit.

B. break 2; should be break 1; to exit both loops.

C. break; cannot be used inside nested loops.

D. break 2; exits only the inner loop.

Solution

1. Step 1: Understand break with levels usage

   break 2; exits two loops, break; exits only the current loop.

2. Step 2: Analyze code logic

   When $i==2 && $j==3, both loops exit with break 2;. When $j==4, only inner loop exits with break;. This matches the requirement.

3. Final Answer:

   Correct use of break with levels to control loop exit. -> Option A

4. Quick Check:

   break n exits n loops, break exits current loop [OK]

Hint: Use break n; for multiple loops, break; for single loop exit [OK]

Common Mistakes:

• Confusing break 2; with break 1;
• Thinking break; exits all loops
• Misusing break levels causing logic errors