Parameters and arguments in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a function that takes one parameter.

PHP

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

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

Agreet

B$greet

C$name

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the $ sign before the parameter name.

Using the function name as a parameter.

The parameter must include the $ sign in PHP, so $name is correct.

2fill in blank

medium

Complete the code to call the function with the argument 'Alice'.

PHP

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

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

Aname

B"Alice"

C$name

DAlice

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the argument without quotes.

Using variable names instead of string literals.

Arguments that are strings must be enclosed in quotes, so "Alice" is correct.

3fill in blank

hard

Fix the error in the function definition by completing the parameter list.

PHP

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

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

A$a, $b

B$a $b

Ca, b

D$a; $b

Attempts:

3 left

💡 Hint

Common Mistakes

Missing commas between parameters.

Omitting $ signs before parameter names.

Parameters must be separated by commas and each must have a $ sign, so $a, $b is correct.

4fill in blank

hard

Fill both blanks to complete the function call with two arguments.

PHP

<?php
function multiply($x, $y) {
    return $x * $y;
}
$result = multiply([1], [2]);
?>

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

A5

B"5"

C10

D"10"

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around numbers unnecessarily.

Passing strings instead of numbers.

Arguments can be numbers without quotes, so 5 and 10 are correct.

5fill in blank

hard

Fill all three blanks to create a function with a default parameter and call it.

PHP

<?php
function greetUser([1] = [2]) {
    echo "Hello, $name!";
}
greetUser([3]);
?>

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

A$name

B"Guest"

C"Alice"

DGuest

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the $ sign in the parameter.

Not using quotes for string default values.

Passing argument without quotes.

The parameter must have a $ sign, the default value must be a string with quotes, and the argument can be a string with quotes.

Practice

1. What is the role of parameters in a PHP function?

easy

A. They are used to store the function's return value.

B. They are the actual values passed to the function during a call.

C. They are variables declared outside the function.

D. They are placeholders for values the function will receive when called.

Solution

1. Step 1: Understand function definition

   Parameters are the names inside the parentheses of a function definition that act as placeholders.

2. Step 2: Differentiate parameters from arguments

   Arguments are the actual values given to the function when it is called, not the placeholders.

3. Final Answer:

   They are placeholders for values the function will receive when called. -> Option D

4. Quick Check:

   Parameters = placeholders [OK]

Hint: Parameters are names in function definition, not actual values [OK]

Common Mistakes:

• Confusing parameters with arguments
• Thinking parameters hold return values
• Assuming parameters are global variables

2. Which of the following is the correct way to define a function with one parameter named name in PHP?

easy

A. function greet(name) { echo "Hello $name"; }

B. function greet(&name) { echo "Hello $name"; }

C. function greet($name) { echo "Hello $name"; }

D. function greet($name) echo "Hello $name";

Solution

1. Step 1: Check parameter syntax in PHP

   In PHP, parameters must have a $ sign before the name inside the function definition.

2. Step 2: Validate function body syntax

   The function body must be enclosed in curly braces {} to be valid.

3. Final Answer:

   function greet($name) { echo "Hello $name"; } -> Option C

4. Quick Check:

   Parameters need $ and braces [OK]

Hint: Parameters always start with $ in PHP function definitions [OK]

Common Mistakes:

• Omitting $ before parameter name
• Missing curly braces around function body
• Using & without purpose

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. Error: Missing return statement

D. 7.0

Solution

1. Step 1: Understand function call with arguments

   The function add receives 3 and 4 as arguments for $a and $b respectively.

2. Step 2: Calculate the return value

   The function returns the sum 3 + 4 = 7, which is then printed by echo.

3. Final Answer:

   7 -> Option A

4. Quick Check:

   3 + 4 = 7 [OK]

Hint: Add numeric arguments to get sum output [OK]

Common Mistakes:

• Concatenating numbers as strings
• Expecting float output without decimals
• Thinking function lacks return

4. Identify the error in this PHP function call:

function greet($name) {
  echo "Hello, $name!";
}
greet();

medium

A. Missing argument for the parameter $name in the function call.

B. Function name is incorrect.

C. Echo statement syntax is wrong.

D. Function definition is missing curly braces.

Solution

1. Step 1: Check function parameters and call

   The function greet requires one parameter $name, but the call provides none.

2. Step 2: Understand PHP behavior on missing arguments

   Calling a function without required arguments causes an error in PHP.

3. Final Answer:

   Missing argument for the parameter $name in the function call. -> Option A

4. Quick Check:

   Required parameter missing in call [OK]

Hint: Always pass required arguments matching parameters [OK]

Common Mistakes:

• Calling function without required arguments
• Assuming default values without specifying
• Ignoring error messages about missing parameters

5. Consider this PHP function:

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

// What is the output of echo multiply(5); ?

hard

A. 5

B. 10

C. Error: Missing argument for second parameter

D. 7

Solution

1. Step 1: Identify default parameter usage

   The second parameter $y has a default value of 2, so it is optional when calling the function.

2. Step 2: Evaluate function call with one argument

   Calling multiply(5) uses 5 for $x and default 2 for $y, so returns 5 * 2 = 10.

3. Final Answer:

   10 -> Option B

4. Quick Check:

   Default parameter used, 5 * 2 = 10 [OK]

Hint: Default parameters fill missing arguments automatically [OK]

Common Mistakes:

• Expecting error when argument is missing for default parameter
• Ignoring default parameter values
• Confusing default parameter position