PHP Developer Interview Questions and Answers

There is a list of the top frequently asked PHP Interview Questions and Answers given below.

1. What does PHP stand for?

Ans – Hypertext Preprocessor

2. Which programming language does PHP resemble?

Ans – PHP syntax resembles Perl and C.

3. How do you define a variable in PHP?

Ans – In PHP, a variable defines with the $ sign, It is followed by the name of the variable. It has the following syntax:

$txt = "Welcome to Webeduclick!";

4. What is a NULL variable?

Ans – NULL variable: In PHP, It is a special data type that is used to denote the presence of only one value, NULL. You can’t assign any other value to it. It has the following syntax:

$var = NULL;       

Alternative way,

$var = null;

5. How do you define a constant in PHP?
Ans – Constant: It is an identifier for a simple value. Constant is just like variables except that once they are defined they cannot be changed or undefined. In PHP, there is no need to use the dollar sign($) before constants. It has the following syntax:

define(name, value, case-insensitive);

Alternative way,

In PHP, The [php]const[/php] keyword is also used to create a constant. It is a language construct, not a function. The [php]const[/php] keyword is case-sensitive. It has the following syntax:

constant (name);

6. How many data types are in PHP?

Ans – There are mainly eight types of data types in PHP.

i. Integer

ii. Double

iii. Boolean

iv. Null

v. String

vi. Array

vii. Object

viii. Resource

7. What are the different types of Array in PHP?

Ans – In PHP, there are three types of arrays:

[no-highlight]i. Indexed arrays
ii. Associative arrays
iii. Multidimensional arrays
[/no-highlight]

8. Difference between “echo” and “print” in PHP?

Ans –
1. echo can pass multiple arguments.
print cannot pass multiple arguments.

2. echo doesn’t return any value.
print always returns 1.

3. echo is much faster than a print statement.
print is slower than the echo statement.

9. Define ‘PHP Escape sequences‘

Ans – PHP Escape sequences: In PHP, Escape sequence is use for escaping a character during the string parsing. It is the combination of the escape character \ and a letter that is used to signify the character.

Example:

1. \' – It is used to escape ' within a single-quoted string.
2. \" – It is used to escape “ within a double-quoted string.
3. \\ – It is used to escape the backslash.
4. \n – It is used to add line breaks between the string.
5. \$ – It is used to escape $.

10. How can we create a database using PHP and MySQL?

Ans –
i. At first, establish a connection to the MySQL server from your PHP script.

ii. If the connection is successful, write a SQL query to create a database and store it in a string variable.

iii. Finally execute the SQL query.

Example:

$server = "localhost";
$user = "root";
$pass = "password";
$db = "dbtest";

// Create connection
$conn = mysqli_connect($server, $user, $pass,$db);

// Check connection
if (!$conn) {
   die("Connection failed: " . mysqli_connect_error());
}
echo "Connected successfully";

11. Difference between the GET and POST methods.

Ans –
1. In PHP, GET used for viewing something, without changing it.
In PHP, POST uses for changing something.

2. GET is used to retrieve remote data.
POST is used to insert/update remote data.

12. Mention some popular frameworks in PHP.

Ans –
i. CodeIgniter
ii. CakePHP
iii. Laravel
iv. Yii 2
v. Zend Framework
vi. Symfony
vii. FuelPHP

13. What are the main features of PHP 7?

Ans –
Main Features of PHP 7:
1. Null coalescing operator

2. Scalar-type declarations

3. Return type declarations

4. Spaceship operator

5. Constant arrays using define()

6. Anonymous classes

7. Generator Return Expressions

8. Generator Delegation

9. Closure::call() method

10. Error Handling

14. How does the ‘for each’ loop work in PHP?

Ans – The for-each loop is used to loop through each key/value pair in an array. It has the following syntax:

foreach ($array_name as $value) {
  statement;
}

15. Difference between require() and require_once() functions.

Ans – [php]require[/php] function will include the file irrespective of whether the file is already included or not.

[php]require_once[/php] will check whether the file is already included or not if it is already included then it would not include the file.

16. What is the use of the function [php]imagetypes()[/php]?

Ans – This function provides the image format in PHP. It is supported by the current version of GD-PHP.

17. How are comments used in PHP?

Ans – Comments are written within the block of PHP code to define the functionality of the code. In PHP, a single-line comment begins with //.

Example:

    $conn = mysqli_connect($server, $user, $pass,$db);    // Create connection

In PHP, multi-line line comment begins with /* and ends with */.

18. Difference between [php]mysqli_fetch_object()[/php] and [php]mysqli_fetch_array()[/php]?

Ans – The [php]mysqli_fetch_object()[/php] function collects the first single matching record.

The [php]mysqli_fetch_array()[/php] function collects all matching records from the table in an array.

19. How to use the Ternary Operator in PHP?

Ans – Ternary Operator: It is a conditional operator that decreases the length of code while performing comparisons and conditionals. It has the following syntax:

(Condition) ? (Statement1) : (Statement2);

20. What is a ‘Null Coalescing’ Operator in PHP?

Ans – The Null Coalescing operator is used to check whether the variable is null or not. It returns the non-null value from the pair of customized values. It has the following syntax:

(Condition) ? (Statement1) ? (Statement2);