Return values in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does a return value do in a PHP function?

A return value sends data back from a function to the place where the function was called. It lets the function give back a result.

beginner

How do you return a value from a PHP function?

Use the return keyword followed by the value you want to send back. For example: return 5;

beginner

What happens if a PHP function has no return statement?

The function returns NULL by default, meaning it does not send any specific value back.

intermediate

Can a PHP function return different types of values?

Yes, a PHP function can return any type of value like numbers, strings, arrays, or even objects.

intermediate

What is the effect of a return statement inside a PHP function?

It immediately stops the function and sends the specified value back to the caller.

What keyword is used to send a value back from a PHP function?

A echo

B return

C output

D send

The return keyword is used to send a value back from a function.

What does a PHP function return if it has no return statement?

A NULL

B 0

C false

D empty string

If no return statement is present, PHP functions return NULL by default.

Which of these can a PHP function return?

A Only numbers

B Only strings

C Any data type like numbers, strings, arrays

D Nothing

PHP functions can return any data type including numbers, strings, arrays, and objects.

What happens after a return statement is executed in a PHP function?

A The function continues running

B The function pauses

C The function restarts

D The function stops and returns the value

A return statement immediately stops the function and sends the value back.

Which of these is NOT a valid return value in PHP?

A A CSS style

B An array

C A function call

D An integer

CSS styles are not valid return values; PHP functions return data types like integers, arrays, or function results.

Explain how the return statement works in a PHP function and why it is useful.

Think about how you get answers from a function after it runs.

Describe what happens if a PHP function does not have a return statement.

What does the function give back by default?

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