Return values in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to return the sum of two numbers.

PHP

<?php
function add($a, $b) {
    return [1];
}

echo add(3, 4);

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

A$a * $b

B$a - $b

C$a + $b

D$a / $b

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction (-) instead of addition (+).

Forgetting to use the return keyword.

The function should return the sum of $a and $b, so return $a + $b; is correct.

2fill in blank

medium

Complete the code to return the length of a string.

PHP

<?php
function getLength($str) {
    return [1];
}

echo getLength("hello");

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

Asize($str)

Bstrlen($str)

Clength($str)

Dcount($str)

Attempts:

3 left

💡 Hint

Common Mistakes

Using count() which is for arrays.

Using non-existent functions like size() or length().

In PHP, strlen() returns the length of a string.

3fill in blank

hard

Fix the error in the function to return the first element of an array.

PHP

<?php
function firstElement($arr) {
    return [1];
}

echo firstElement([10, 20, 30]);

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

A$arr[0]

B$arr(0)

C$arr->0

Darr[0]

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses instead of square brackets.

Trying to access array elements as object properties.

To access the first element of an array in PHP, use square brackets with index 0: $arr[0].

4fill in blank

hard

Fill both blanks to return a new array with squares of numbers greater than 3.

PHP

<?php
function squaresAboveThree($numbers) {
    return array_combine(
        array_filter($numbers, fn($n) => $n [1] 3),
        array_map(fn($n) => $n[2]2, array_filter($numbers, fn($n) => $n > 3))
    );
}

print_r(squaresAboveThree([1, 2, 3, 4, 5]));

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

A>

B*

C**

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication (*) instead of exponentiation for squaring.

Using less than (<) instead of greater than (>) for filtering.

The function filters numbers greater than 3 using > and squares them using the exponent operator **.

5fill in blank

hard

Fill all three blanks to return an associative array with uppercase keys and values greater than 10.

PHP

<?php
function filterAndUppercase($data) {
    $result = [];
    foreach($data as [3] => [2]) {
        if([2] > 10) {
            $result[[1]] = [2];
        }
    }
    return $result;
}

print_r(filterAndUppercase(['a' => 5, 'b' => 15, 'c' => 20]));

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

Astrtoupper($key)

B$value

C$key

D$item

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable names for keys or values.

Not converting keys to uppercase.

The function returns an array with keys converted to uppercase using strtoupper($key), values as $value, and iterates over $key in the input array.

Practice

1. What does the return statement do inside a PHP function?

easy

A. It declares a new variable inside the function.

B. It prints a value on the screen.

C. It stops the entire script immediately.

D. It sends a value back to where the function was called.

Solution

1. Step 1: Understand the purpose of return

   The return statement sends a value back to the place where the function was called.

2. Step 2: Differentiate from other actions

   It does not print or stop the whole script; it only ends the function and sends back a value.

3. Final Answer:

   It sends a value back to where the function was called. -> Option D

4. Quick Check:

   Return sends value back [OK]

Hint: Return sends value back to caller, not print or stop script [OK]

Common Mistakes:

• Thinking return prints output
• Confusing return with exit or die
• Assuming return declares variables

2. Which of the following is the correct syntax to return the value 10 from a PHP function?

easy

A. return 10;

B. return(10)

C. return = 10;

D. return: 10;

Solution

1. Step 1: Recall PHP return syntax

   The correct syntax uses the keyword return followed by the value and a semicolon: return 10;

2. Step 2: Identify syntax errors in other options

   A uses invalid assignment; return(10) misses semicolon; D uses colon incorrectly.

3. Final Answer:

   return 10; -> Option A

4. Quick Check:

   Return value ends with semicolon [OK]

Hint: Return value with semicolon, no assignment or colon [OK]

Common Mistakes:

• Omitting semicolon after return
• Using assignment operator with return
• Using colon instead of semicolon

3. What will be the output of this PHP code?

function add($a, $b) {
  return $a + $b;
  echo "Done";
}
$result = add(3, 4);
echo $result;

medium

A. 7

B. Done7

C. 7Done

D. Error

Solution

1. Step 1: Understand return stops function execution

   The return $a + $b; sends back 7 and stops the function, so echo "Done"; is never run.

2. Step 2: Output the returned value

   The variable $result gets 7, and echo $result; prints 7 only.

3. Final Answer:

   7 -> Option A

4. Quick Check:

   Return stops function, only 7 printed [OK]

Hint: Code after return inside function does not run [OK]

Common Mistakes:

• Expecting code after return to execute
• Confusing echo inside function with return
• Thinking return prints output

4. Identify the error in this PHP function:

function multiply($x, $y) {
  $product = $x * $y;
  return
  $product;
}

medium

A. Missing semicolon after return

B. Return statement split incorrectly, returns nothing

C. Variable $product is undefined

D. Function missing closing brace

Solution

1. Step 1: Analyze the return statement split

   The return is on one line alone, so PHP treats it as returning nothing immediately.

2. Step 2: Understand effect of line break after return

   The next line $product; is unreachable and not part of return, causing function to return null.

3. Final Answer:

   Return statement split incorrectly, returns nothing -> Option B

4. Quick Check:

   Return must be on same line as value [OK]

Hint: Keep return and value on same line to avoid empty return [OK]

Common Mistakes:

• Splitting return and value on separate lines
• Assuming return reads next line automatically
• Ignoring PHP's automatic semicolon insertion

5. You want a PHP function that returns the first non-empty string from an array. Which function correctly returns the first non-empty string or null if none found?

hard

A. function firstNonEmpty(array $arr) {
foreach ($arr as $str) {
if ($str) {
return $str;
}
}
return '';
}

B. function firstNonEmpty(array $arr) {
foreach ($arr as $str) {
if (isset($str)) {
return $str;
}
}
return null;
}

C. function firstNonEmpty(array $arr) {
foreach ($arr as $str) {
if ($str !== '') {
return $str;
}
}
return null;
}

D. function firstNonEmpty(array $arr) {
foreach ($arr as $str) {
if ($str == '') {
return $str;
}
}
return null;
}

Solution

1. Step 1: Check condition for non-empty string

   function firstNonEmpty(array $arr) { foreach ($arr as $str) { if ($str !== '') { return $str; } } return null; } uses $str !== '' to find strings that are not empty exactly.

2. Step 2: Confirm return value if none found

   function firstNonEmpty(array $arr) { foreach ($arr as $str) { if ($str !== '') { return $str; } } return null; } returns null if no non-empty string is found, which is clear and intentional.

3. Final Answer:

   function firstNonEmpty(array $arr) { foreach ($arr as $str) { if ($str !== '') { return $str; } } return null; } -> Option C

4. Quick Check:

   Return first non-empty string or null [OK]

Hint: Use strict check !== '' to find non-empty strings [OK]

Common Mistakes:

• Using loose truthy check that skips '0' string
• Returning empty string instead of null when none found
• Returning on empty string instead of non-empty