How PHP executes on the server - Practice Exercises

Challenge - 5 Problems

❓ Predict Output

intermediate

PHP Script Execution Output

What is the output of this PHP code when executed on a server?

PHP

<?php
function test() {
    static $count = 0;
    $count++;
    return $count;
}

echo test();
echo test();
echo test();
?>

A 321

B 111

C 123

D Syntax Error

💡 Hint

Static variables inside functions keep their value between calls.

The static variable $count inside the function test() retains its value between calls, so it increments each time test() is called, producing 1, then 2, then 3, output as '123'.

🧠 Conceptual

intermediate

PHP Server Execution Flow

Which step correctly describes what happens first when a PHP file is requested by a browser?

A The browser executes the PHP code directly.

B The PHP code is compiled into a binary executable on the client.

C The server sends the PHP code as plain text to the browser.

D The PHP interpreter parses and executes the PHP code on the server.

💡 Hint

Remember where PHP code runs: server or client?

PHP code runs on the server. When a PHP file is requested, the server uses the PHP interpreter to parse and execute the code, then sends the resulting output (usually HTML) to the browser.

🔧 Debug

advanced

Identify the Error in PHP Execution

What error will this PHP code produce when executed on the server?

PHP

<?php
$number = 10;
if ($number = 5) {
    echo "Number is five.";
} else {
    echo "Number is not five.";
}
?>

A Outputs: Number is five.

B Outputs: Number is not five.

C Syntax Error due to assignment in if condition.

D Runtime Error: Undefined variable.

💡 Hint

Check the difference between '=' and '==' in conditions.

The if condition uses '=' which assigns 5 to $number and returns true, so the if block runs and outputs 'Number is five.'. This is a common mistake where '==' (comparison) was intended.

📝 Syntax

advanced

PHP Syntax Error Identification

Which option contains a syntax error that will prevent PHP from executing the script?

PHP

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

A

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

B

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

C

<?php
function greet($name) {
    echo "Hello, $name!";
}
greet("Alice");

D

>?
;)"ecilA"(teerg
}
;"!eman$ ,olleH" ohce    
{ )eman$(teerg noitcnuf
php?<

💡 Hint

Look for missing parentheses or semicolons.

Option A is missing the closing parenthesis in the greet function call, causing a syntax error and preventing execution.

🚀 Application

expert

PHP Output Buffering Behavior

What will be the output of this PHP code when executed on the server?

PHP

<?php
ob_start();
echo "Start-";
ob_clean();
echo "End";
ob_end_flush();
?>

A Start-End

B End

C Start

D No output

💡 Hint

ob_clean() clears the output buffer before sending it.

The output buffer starts and 'Start-' is echoed but then ob_clean() clears the buffer, so 'Start-' is removed. Then 'End' is echoed and finally ob_end_flush() sends the buffer content, which is 'End'.