1. What’s the difference between the include() and require() functions?
They both include a specific file but on require the process exits with a fatal error if the file can’t be included, while include statement may still pass and jump to the next step in the execution.
2. How can we get the IP address of the client?
This question might show you how playful and creative the candidate is because there are many options. $_SERVER["REMOTE_ADDR"]; is the easiest solution, but the candidate can write x line scripts for this question.
3. What’s the difference between unset() and unlink()?
unset() sets a variable to “undefined” while unlink() deletes a file we pass to it from the file system.
4. What is the output of the following code:
$a = '1';
$b = &$a;
$b = "2$b";
echo $a.", ".$b;5. What are the main error types in PHP and how do they differ?
In PHP there are three main type of errors:
- Notices – Simple, non-critical errors that are occurred during the script execution. An example of a Notice would be accessing an undefined variable.
- Warnings – more important errors than Notices, however the scripts continue the execution. An example would be
include()a file that does not exist. - Fatal – this type of error causes a termination of the script execution when it occurs. An example of a Fatal error would be accessing a property of a non-existent object or
require()a non-existent file.
Understanding the error types is very important as they help developers understand what is going on during the development, and what to look out for during debugging.
6. What is the difference between GET and POST?
- GET displays the submitted data as part of the URL, during POST this information is not shown as it’s encoded in the request.
- GET can handle a maximum of 2048 characters, POST has no such restrictions.
- GET allows only ASCII data, POST has no restrictions, binary data are also allowed.
- Normally GET is used to retrieve data while POST to insert and update.
Understanding the fundamentals of the HTTP protocol is very important to have for a PHP developer, and the differences between GET and POST are an essential part of it.
7. How can you enable error reporting in PHP?
Check if “display_errors” is equal “on” in the php.ini or declare “ini_set('display_errors', 1)” in your script.
Then, include “error_reporting(E_ALL)” in your code to display all types of error messages during the script execution.
Enabling error messages is very important especially during the debugging process as one can instantly get the exact line that is producing the error and can see also if the script in general is behaving correctly.
8. What are Traits?
Traits are a mechanism that allows you to create reusable code in languages like PHP where multiple inheritance is not supported. A Trait cannot be instantiated on its own.
It’s important that a developer knows the powerful features of the language (s)he is working on, and Trait is one of such features.
9. Can the value of a constant change during the script’s execution?
No, the value of a constant cannot be changed once it’s declared during the PHP execution.
10. Can you extend a Final defined class?
No, you cannot extend a Final defined class. A Final class or method declaration prevents child class or method overriding.
11. What are the __construct() and __destruct() methods in a PHP class?
All objects in PHP have Constructor and Destructor methods built-in. The Constructor method is called immediately after a new instance of the class is being created, and it’s used to initialize class properties. The Destructor method takes no parameters.
Understanding these two in PHP means that the candidate knows the very basics of OOP in PHP.
12. How we can get the number of elements in an array?
The count() function is used to return the number of elements in an array.
Understanding of arrays and array related helper functions is important for any PHP developer.
13. How would you declare a function that receives one parameter name hello?
If hello is true, then the function must print hello, but if the function doesn’t receive hello or hello is false the function must print bye.
<?php
function showMessage($hello=false){
echo ($hello)?'hello':'bye';
}
?>In this question, you can evaluate if the developer knows how to declare a function and how they would manage the fact of the parameter can or cannot be on the function call. You can also evaluate if the developer knows the if syntax and how to print text(echo function).
14. The value of the variable input is a string 1,2,3,4,5,6,7. How would you get the sum of the integers contained inside input?
<?php
echo array_sum(explode(',',$input));
?>The explode function is one of the most used functions in PHP, so it’s important to know if the developer knows this function. There is no unique answer to this question, but the answer must be similar to this one.
15. How would you implement a class in the following scenario?
Suppose that you have to implement a class named Dragonball. This class must have an attribute named ballCount (which starts from 0) and a method iFoundaBall. When iFoundaBall is called, ballCount is increased by one. If the value of ballCount is equal to seven, then the message You can ask your wish is printed, and ballCount is reset to 0. How would you implement this class?
<?php
class dragonBall{
private $ballCount;
public function __construct(){
$this->ballCount=0;
}
public function iFoundaBall(){
$this->ballCount++;
if($this->ballCount===7){
echo "You can ask for your wish.";
$this->ballCount=0;
}
}
}
?>