Return values in PHP - Mini Project: Build & Apply

Return values

📖 Scenario: You are creating a simple calculator function in PHP that adds two numbers and returns the result.

🎯 Goal: Build a PHP function that takes two numbers, adds them, and returns the sum. Then display the returned value.

📋 What You'll Learn

Create a function named addNumbers that takes two parameters: $a and $b.

Inside the function, return the sum of $a and $b.

Call the function with the numbers 5 and 7 and store the result in a variable named $result.

Print the value of $result.

💡 Why This Matters

🌍 Real World

Functions that return values are used everywhere in programming to get results from calculations or data processing.

💼 Career

Understanding return values is essential for writing reusable code and working with APIs, libraries, and frameworks in professional PHP development.

1

Create the function skeleton

Write a PHP function named addNumbers that takes two parameters: $a and $b. Do not add any code inside the function yet.

PHP

<?php

// Your code here

Hint

Use the function keyword followed by the function name and parameters in parentheses.

2

Add the return statement

Inside the addNumbers function, write a return statement that returns the sum of $a and $b.

PHP

<?php
function addNumbers($a, $b) {
    // Your code here
}

Hint

Use return $a + $b; to send back the sum.

3

Call the function and store the result

Call the addNumbers function with arguments 5 and 7, and store the returned value in a variable named $result.

PHP

<?php
function addNumbers($a, $b) {
    return $a + $b;
}

// Your code here

Hint

Use $result = addNumbers(5, 7); to call the function and save the answer.

4

Print the result

Print the value of the variable $result using echo.

PHP

<?php
function addNumbers($a, $b) {
    return $a + $b;
}

$result = addNumbers(5, 7);

// Your code here

Hint

Use echo $result; to display the sum.

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