Function declaration and calling in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a function named greet.

PHP

<?php
function [1]() {
    echo "Hello!";
}
?>

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

Ahello

BprintMessage

CsayHello

Dgreet

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different function name than the one called.

Forgetting to write the function keyword.

The function name must be greet to match the call later.

2fill in blank

medium

Complete the code to call the function greet.

PHP

<?php
greet[1];
?>

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

A()

B{}

C[]

D;

Attempts:

3 left

💡 Hint

Common Mistakes

Calling the function without parentheses.

Using curly braces or square brackets instead of parentheses.

Functions in PHP are called with parentheses () even if they have no parameters.

3fill in blank

hard

Fix the error in the function declaration to accept one parameter named name.

PHP

<?php
function greet([1]) {
    echo "Hello, $name!";
}
?>

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

A$name

B*name

C&name

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the dollar sign in the parameter.

Using pointer or reference symbols incorrectly.

In PHP, function parameters must have a dollar sign $ before the variable name.

4fill in blank

hard

Fill both blanks to call the greet function with the argument 'Alice'.

PHP

<?php
greet([1][2]);
?>

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

AAlice

B"Alice"

C'Alice'

DAlice()

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the argument without quotes.

Using a function call instead of a string.

The argument must be a string with quotes. Single quotes or double quotes work, but only one option can be chosen here. The second blank is empty because the quotes include the whole string.

5fill in blank

hard

Fill all three blanks to declare a function named add that takes two parameters and returns their sum.

PHP

<?php
function [1]([2], [3]) {
    return $a + $b;
}
?>

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

Aadd

B$a

C$b

Dsum

Attempts:

3 left

💡 Hint

Common Mistakes

Using parameter names without $.

Using a different function name than add.

The function name is add. The parameters must be variables with $ signs: $a and $b.

Practice

1. What is the correct way to declare a function named greet in PHP?

easy

A. function greet() { }

B. def greet() { }

C. func greet() { }

D. function: greet() { }

Solution

1. Step 1: Recognize PHP function declaration syntax

   In PHP, functions are declared using the keyword function followed by the function name and parentheses.

2. Step 2: Match the correct syntax

   function greet() { } uses function greet() { }, which is the correct PHP syntax for declaring a function named greet.

3. Final Answer:

   function greet() { } -> Option A

4. Quick Check:

   PHP function declaration = function greet() { } [OK]

Hint: Use 'function' keyword to declare functions in PHP [OK]

Common Mistakes:

• Using 'def' instead of 'function'
• Adding a colon after 'function'
• Using 'func' keyword which is not valid in PHP

2. Which of the following is the correct way to call a function named sayHello in PHP?

easy

A. call sayHello();

B. sayHello();

C. sayHello;

D. callFunction(sayHello);

Solution

1. Step 1: Understand PHP function call syntax

   In PHP, to call a function, you write the function name followed by parentheses, optionally with arguments inside.

2. Step 2: Identify the correct option

   sayHello(); uses sayHello();, which is the correct way to call the function named sayHello.

3. Final Answer:

   sayHello(); -> Option B

4. Quick Check:

   Function call syntax = sayHello(); [OK]

Hint: Call functions by name with parentheses () [OK]

Common Mistakes:

• Using 'call' keyword which does not exist in PHP
• Omitting parentheses when calling functions
• Using incorrect function call syntax like callFunction()

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

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

medium

A. 7

B. 34

C. add(3, 4)

D. Error

Solution

1. Step 1: Understand the function behavior

   The function add takes two parameters and returns their sum.

2. Step 2: Calculate the return value

   Calling add(3, 4) returns 3 + 4 = 7, which is then printed by echo.

3. Final Answer:

   7 -> Option A

4. Quick Check:

   3 + 4 = 7 [OK]

Hint: Functions return values; echo prints the result [OK]

Common Mistakes:

• Concatenating numbers as strings instead of adding
• Expecting function name to print instead of return value
• Syntax errors from missing semicolons

4. Identify the error in the following PHP code:

function greet() {
    echo "Hello!";
}
greet;

medium

A. Missing semicolon after function declaration

B. Function name is incorrect

C. Missing parentheses when calling the function

D. Echo statement syntax error

Solution

1. Step 1: Check function call syntax

   The function greet is declared correctly, but when calling it, parentheses are missing.

2. Step 2: Understand PHP function call requirements

   In PHP, functions must be called with parentheses, even if they take no arguments. So greet; is invalid; it should be greet();.

3. Final Answer:

   Missing parentheses when calling the function -> Option C

4. Quick Check:

   Function calls need () even if no arguments [OK]

Hint: Always use () to call functions, even if empty [OK]

Common Mistakes:

• Calling functions without parentheses
• Confusing function declaration with call
• Missing semicolons elsewhere

5. Consider the following PHP code:

function multiply($x, $y = 2) {
    return $x * $y;
}
echo multiply(5);

What will be the output and why?

hard

A. 0 because default value is ignored

B. 5 because only one argument is passed

C. Error because both parameters are required

D. 10 because the second parameter uses default value 2

Solution

1. Step 1: Understand default parameter usage

   The function multiply has two parameters, where $y has a default value of 2.

2. Step 2: Analyze the function call

   Calling multiply(5) passes 5 as $x, and since $y is not provided, it uses the default 2.

3. Step 3: Calculate the result

   The function returns 5 * 2 = 10, which is printed by echo.

4. Final Answer:

   10 because the second parameter uses default value 2 -> Option D

5. Quick Check:

   5 * 2 = 10 with default parameter [OK]

Hint: Default parameters fill missing arguments automatically [OK]

Common Mistakes:

• Assuming all parameters must be passed
• Ignoring default values
• Expecting error when missing arguments