In this article, you will get the most important PHP interview questions with answers 2021. It will be helpful to qualify for the technical interview. All the PHP questions contain the best example with an explanation. So, these questions will increase your confidence level for the interview.
If you are a Web developer and your working technology is PHP. You will have to face the technical interview round. But you have no idea of PHP questions that will be asked by the interviewer. So, It’s a big problem for PHP developers.
Don’t worry, I’m also a full-stack developer and I have faced many interviews. In each interview, Interviewer asked me common questions that are necessary for developers. So, I have collected these PHP Interview Questions and Answers according to my working experience.
Top PHP Technical Interview Questions and Answers
I have shared the top 70 PHP Interview Questions and Answers that can help you to raise your confidence in the technical interview round. Even you will definitely get a respected job in the web development field.
Read Also
JavaScript Interview Questions and Answers 2021
Now, I’m going to explain PHP interview Questions with answers and examples through the following steps.
Most Important PHP Interview Questions
All the PHP Interview questions of this category are given for beginners and experienced developers. Generally, interviewers ask these types of questions. Because they want to check the coding level of developers so that they should select him/her for the next round.
1. What is PHP?
PHP is the back-end scripting language that runs on the server.
We can use the PHP script to make dynamic web pages.
We can use PHP absolutely free for the web project.
PHP is the short form of Hypertext Preprocessor
2. What is the old name of PHP?
Personal Home Page
3. What is the current version of PHP
The current version of PHP: 7.4.6
Click here to check PHP current version –
4. What are the differences between echo & print?
PHP Echo
echocan accept multiple statements separated by the comma.- It runs faster than print.
- It doesn’t return any value.
PHP Print
printcan accept only a single statement.- It runs slower than echo
- It always returns 1
5. What are the 10 string functions?
strlen()explode()implode()str_rev()str_word_count()trim()str_replace()md5()strtolower()strtoupper()
Read an explanation of the above functions
6. How many types of the array?
The array is divided into three categories
- Indexed Array
- Associative Array
- Multi-dimensional Array
Read an explanation of the above arrays
7. What are the 10 array functions?
count()array_combine()array_merge()array_push()array_pop()array_revers()array_sum()array_product()ksort()krsort()
Read an explanation of the above functions
8. What is the difference between include() & require?
PHP include()
When We pass an unknown file to the include() function to use into another file, It will generate a warning error and will continue the execution of the next script.
Suppose that, you have included a file into another page using include() function and that file does not exist in your project folder. then you will get a warning error and will continue the execution of the next script.
PHP require()
When We pass an unknown file to the require() function to use into another file, It will generate a fatal error and stop the execution of the next script.
Suppose that, you have included a file into another page using require() function and that file does not exist in your project folder. then you will get a fatal error and will stop the execution of the next script
9. What is the difference between include & include_once?
We can use include() multiple times in a file to include files.
We can use include_once() only one time in a file to include files
10. What are the differences between post & get?
post Method
- When we send data using
post, it will not display in the browser URL bar - In the case of
post, We can send an unlimited amount of data to the server. postdata is always secured- We can’t bookmark
postdata to the browser postdata will not save in browser history
get Method
- When we send data using
get, it will display in the browser URL bar - In the case of
get, We can send a limited amount of data to the server. getdata is less secured- We can bookmark
getdata to the browser getdata will not save in browser history
11. What are the superglobal variables?
$_GET['variableName']$_POST['variableName']$_GET['variableName']$_REQUEST['variableName']$_FILES['variableName']$_SESSION['variableName']$_COOKIE['variableName']$_SERVER['variableName']
12. What is the difference between session & cookies?
Session
- The
sessionis stored in the server as a temporary variable. - It has no restriction on data, it can store an unlimited amount of data
- It will be destroyed after closing the browser
- The
sessionis more secure than cookies
Cookies
Cookiesare stored in the browser as a text file.- It has a restriction on data, it can store only a limited amount of data.
- It will not be destroyed after closing the browser.
Cookiesare less secure than the session.
13. What is difference between == and ===?
double equal ==
In the case of double equal==, comparison variables must have the same values to return true.
Suppose that, when we compare two variables using double equal==, it will return true. if the values of both variables are equal.
$a=20; // integer type
$b="30"; // string type
if($a==$b)
{
echo "I am true";
}
else
{
echo "I am False";
}Triple equal===
In the case of triple equal ===, comparison variables must have the same values as well as the same data type to return true.
Suppose that when we compare two variables using triple equal ===. it will return true. if the values and datatype of both variables are equal
$a=20; // integer type
$b="30"; // string type
if($a===$b)
{
echo "I am true";
}
else
{
echo "I am False";
}14. What is the difference between for loop and foreach loop?
for loop
- It has a condition to execute at the specified times.
- It can be used for an indexed array.
Example-
Suppose that, We have to print numbers 1 to 10, then we have to use for loop. because we know that loop will run 10 times
for($i=1;$i<=10;$i++)
{
echo $i." ";
}We can use for loop for indexed array because we can find a number of times to execute it using count() method.
$arr=["noor","sunil","Amit","Anil"];
for($i=0;$i<count($arr); $i++)
{
echo $arr[$i]." ";
}foreach Loop
- It has no condition to execute at specific times.
- It can be used for an indexed array and associative array.
Example –
Suppose that, We have to print numbers 1 to 10, then we can’t use foreach loop. because it has no condition to declare a number of times
$arr=["noor","sunil","Amit","Anil"];
foreach($arr as $val)
{
echo $val." ";
}
We can use foreach for indexed array and associative array because we need not declare the condition.
$arr=["name"=>"Noor","age"=>25,"city","Patna"];
foreach($arr as $val)
{
echo $val." ";
}15. What are the new features of PHP7?
- Constant arrays using define()
- Scalar type declarations
- Return type declarations
- Group use declaration
- Null coalescing operator (??)
- Spaceship operator
- Anonymous classes
- Closure::call method
- Generator delegation
Read Explanation of above features
16. What is the difference between array_merge & array_combine?
array_merge()
We can merge one or more arrays into one array using array_merge() function.
Example -1
This example merges two index arrays
for indexed array
$arr1=array("Mohan","Radha","Amit");
$arr2=array("Sunil","Monika");
$mrg=array_merge($arr1,$arr2);
print_r($mrg);Example – 2
This example merges two associative array
//for an indexed array
$assoc1=array("a"=>Mohan","b"=>"Radha","c"=>"Amit");
$assoc2=array("d"=>"Sunil","d"=>"Monika");
$mrg2=array_merge($assoc1,$assoc2);
print_r($mrg2);Example – 3
This example pass an associative array as a parameter to the array_merge()
//for an indexed array
$assoc1=array("a"=>Mohan","b"=>"Radha","c"=>"Amit");
$mrg3=array_merge($assoc1);
print_r($mrg3);array_combine()
We can create an array with keys of one array and values of another array using array_combine() function.
Example -1
$arr1=array("Mohan","Radha","Amit");
$arr2=array("20","30","10");
$mrg=array_merge($arr1,$arr2);
print_r($mrg);17. What is the $this keyword?
$this is a representation of the current object of a class.
We must have to use a variable inside a method of a class using $this keyword.
Example
class Boy{
public $profile="Developer";
public function get_profile(){
$result=$this->profile;
return $result;
}
}
$obj=new Boy();
echo $obj->get_profile(); // it returns Developer18. What is the constructor?
The constructor is the special type of method of a class.
It will execute automatically after creating an object.
Normally, We have to access the custom method from an object of a class but we need not access the constructor method from an object.
Syntax –
function__construct(){}
Example:
class Boy {
public $name="Noor khan";
public $age=25;
function __construct() {
echo $this->name;
}
function get_age() {
echo $this->age;
}
}
$obj = new Boy();
echo "<br>";
$obj->get_age();19. What are the access modifiers?
There are three access modifiers such as
- public – If we declare properties or methods with the public modifier, we can access it from anywhere.
- protected – If we declare properties or methods with the protected modifier, we can access it within its current class and into child class of that current class as well
- private – If we declare properties or methods with the private modifier, we can access it only within its current class.
class Boy {
public $name;
protected $age;
private $city;
}
$obj = new Boy();
$obj->name = 'Noor Khan';
$obj->age = 25; // It produces an error
$obj->city = 'Patna'; // It produces an error20. What inheritance and explain different types of inheritance?
Inheritance
In the case of Inheritance, a class inherits all the properties & methods from another class with extends keyword.
- Single Inheritance
- Multiple Inheritance
- Multilevel Inheritance
- Hierarchical Inheritance
- Hybrid Inheritance.
21. What is Single Inheritance
In this inheritance, We can create only one class from the other one class.
The created class will be child class and the other one class will be the parent class.
Child class may have its own properties & methods and it will also inherit all the properties & methods of the parent class.
Example
Suppose that, We have to create class Two from class One like the following derivation.
class One{
public $a=50;
public $b=20;
public function addition(){
$sum=$a+$b;
echo $sum;
}
}
class Two extends One{
public function subtraction(){
$sub=$a-$b;
echo $sub;
}
}
22. What is Multiple Inheritance
In this inheritance, We can create a child class from more than one parent class.
PHP does not support multiple Inheritance.
Example
Suppose that, We will create class Three from class One & class Two as the following derivation
Multi-level Inheritance
23. What is Multi-level Inheritance
In this inheritance, We can create a child class from a parent class and again another child class from the created child class.
Example –
Suppose that, We will create a child class two from parent class one and another child class three from created child class two as the following derivation.
class One{
public $a=50;
public $b=20;
public function addition(){
$sum=$a+$b;
echo $sum;
}
}
class Two extends One{
public function subtraction(){
$sub=$a-$b;
echo $sub;
}
}
class Three extends Two{
public function multiplication(){
$mul=$a*$b;
echo $mul;
}
}24. What is Hierarchical Inheritance
In this inheritance, We can create more than one child classes from a single parent class.
Suppose that, We will create child class Two and another child class Three from parent class One as the following derivation.
class One{
public $a=50;
public $b=20;
public function addition(){
$sum=$a+$b;
echo $sum;
}
}
class Two extends One{
public function subtraction(){
$sub=$a-$b;
echo $sub;
}
}
class Three extends one{
public function multiplication(){
$mul=$a*$b;
echo $mul;
}
}25. Hybrid Inheritance
In this inheritance, We can create multiple classes by the combination of Multi-level, multiple & Hierarchical inheritance.
26. What is the difference between abstract & interface?
In PHP language, use of abstract class & interface are approx similar but some following points are absolutely different from each other
Abstract Class
- In abstract class, We need not declare every method as an abstract
- We can define as well as declare methods in the abstract class
- We can declare methods of an abstract class with the public or protected both modifiers
- In abstract class, We can declare the constructor method.
- We can declare data members in an abstract class.
Interface
- In the interface, We have to declare every method as an abstract
- We can only define methods in the interface.
- We can only declare methods of interface with the public modifier.
- In the interface, W can’t declare the constructor method
- We can’t declare data members in an interface
27. What is a trait?
The trait is similar to a class but we can’t create an object from trait.
We can only use traits inside one or more classes with the use keyword.
Generally, We can use the traits for the purpose of the multiple inheritances.
Example –
<?php
trait One {
public function traitOne() {
echo 'I am trait one';
}
}
trait Two {
public function traitTwo() {
echo 'I am trait Two';
}
}
class Three {
use One, Two;
public function myFun() {
echo 'I am a class';
}
}
$obj = new Tree();
$obj->traitOne();
$obj->traitTwo();
$obj->myFun();
?>28. What is a namespace?
The namespace is just like a folder.
The namespace is used to manage classes or methods of the same name that remain in the same file.
We can’t declare more than one class or method with the same name into a single file as the following code.
// declared two classes with the same name
class Work{
public function myTask(){
echo "I am learning namespace";
}
}
class Work{
public function ypurTask(){
echo "I am learning namespace";
}
}
// declared two methods with same name
public function myName(){
echo "My Name is namespace";
}
public function myName(){
echo "My Name is namespace";
}
But We can declare the above code with the namespace as following code.
// declared two classes with the same name
namespace abc{
class Work{
public function myTask(){
echo "I am namespace abc";
}
}
}
namespace xyz{
class Work{
public function ypurTask(){
echo "I am namespace xyz";
}
}
}
// declared two methods with same name
namespace ab{
function myName(){
echo "My Name is namespace ab";
}
}
namespace{
public function myName(){
echo "My Name is namespace";
}
$onj1=new abc\Work();
$obj1->myTask(); // output- I am namespace abc
$obj2=new xyz\Work();
$obj2->yourTask(); // output- I am namespace xyz
myname(); // output- My Name is namespace
ab\myname(); // output- My Name is namespace ab
}The namespace has some following rule
- We can’t declare namespaces of the same name in the single file.
- We can’t write any PHP codes outside the namespace.
29. What is the self keyword in PHP
Self represents static properties & methods of the current class.
Suppose that we have declared a variable with static keyword into the class like public status $name=”codingStatus” and a method like public myName(){}. Now I want to access $name into myName(){} function.then We can access like the following code
class Coding{
public static $name="codingStatus";
public function myName(){
echo "My Name is ".self::name;
}
}30. What are the differences between self and this keyword?
self keyword
selfis a representation of static properties & methods of a class.- It will access the properties or methods using scope resolution operator
:: - It does not begin with any symbol.
this keyword
$thisis a representation of the current object of a class.- It will access the properties or methods using the arrow operator
-> - It always begins
$symbol
31. What is Type Hinting
Type Hinting is the concept of passing array & object type variables to the function by declaring their datatype.
// passing an array
function detail(array $data){
perint_r($data);
}
$data=["Noor",24,"Patna"];
detail($data);
//passing an object
class Boy{
function __construct()
{
echo "I am Boy Type class";
}
}
$onj=new Boy();
detail(Boy $obj);32. Write the mail function?
$to="receiver@gmail.com"; // Write the email id of mail receiver $subject="php interview questino"; // Write your mail title $message="You have best otiopn to learn php interview questions"; // write your message $headers.="From:sender@gmail.com"; // write sender name or email id mail($to,$subject,$message,$headers);
33. What is the query string?
The query string is used to pass the value from a page to another page through its URL.
Syntax-
url?object=value&object=value
Example – 1
Create a single query string in the following url
<a href="my-url.php?name=noor">Click here</a> <a href="my-url.php?id=3">Get id</a>
Get value in my-url.php file using the following script
<?php $name= $_GET['name']; $id= $_GET['id']; ?>
Example – 2
Create two query string in a single URL
<a href="my-url.php?name=noor&id=3">Click here</a>
Get value my-url.php page
<?php $name= $_GET['name']; $id= $_GET['id']; ?>
34. What is the recursive function?
When a function calls itself within its own body to execute several times.it will be a recursive function.
Example –
function number ($num)
{
if ($num <= 0) return "Negative integer is not allowed";
if ($num > 9) return "Counting is completed";
else return number ($num+1);
}35. What is the difference between implode() & explode()?
explode() function
- it is used to create an array by breaking a string.
- separator argument of
explode()is required.
Syntax –
explode('separator','string');
Example –
$expStr="I am explode() function";
$expArr=explode(' ',$expStr);
print_r($expArr);implode() function
- It is used to create a string by joining elements of an array
- separator argument of
implode()is optional.
Syntax –
implode('separator','string');
Example –
$impArr=array('I','am','implode()','function');
$impstr=implode('',$impArr);
echo $impstrBasic PHP Interview Questions for Freshers
These are the collection of basic level questions answers for face to face interview round.
These questions are more necessary for fresher developers and Experienced developers can prepare as well.
1. What We can do in PHP
We can do the following things
- Dynamic content of the web page.
- Create, read, write, open, close and delete files on the server
- Insert,edit,update,delete data in the table
2. Is PHP variable a Case Sensitive?
Yes, because $var and $VAR are different from each other
3. What is difference between define() & constant()
define() is used to create a constant variable.
constant() is to display the value of a constant variable.
Example –
define("codingstatus","Free coding tutorias for IT developers");
echo constant("codingstatus");4. What is the magic constant?
Magic constant is the predefined function.
It has the double underscore__at the beginning and ending
Its value depends on where it is used.
Example
__LINE__ It returns the current line of its declaration.
echo "It is line no ".__LINE__; // it returns- It is line no 1 echo "It is line no ".__LINE__; // it returns- It is line no 2 echo "It is line no ".__LINE__; // it returns- It is line no 3
5. What are the different type of magic constants
PHP provides the following different types of magic constants
__LINE__
__DIR__
__FILE__
__FUNCTION__
__METHOD__
__NAMESPACE__
__CLASS__
__TRAIT__
6. How to find the string length in PHP?
We can calculate string length using strlen()
Example –
$str="I am codingStatus"; echo strlen($str);
7. What is XSS?
XSS is the short form of cross-site-scripting.
It allows hackers to insert front-end script to the web pages
8. Can we use a double quote inside another double quote?
No, because PHP allows us to use double quote inside a single code
9. What is isset() function?
We can check the variable is set or not using isset().
If the variable is set. it will return true otherwise false
If it has a null value will return false.
var $var="codingStatus";
if(isset($var)){
echo "variable is set";
}
else{
echo "variable is not set";
}
// for nul value
var $nullvar=null;
if(isset($nullvar)){
echo "variable is set";
}
else{
echo "variable is not set";
}10. What are the differences between while loop and the do-while loop?
While Loop
Whileloop checks the condition at the beginning of the loop- If the condition of the
whileloop will be false then the loop will not run. - The end of the
whileloop is not terminated by a semicolon.
do-while loop
do-whileloop checks the condition at the ending of the loop- If the condition of the
do-whileloop will be false then the loop will run at least once. - The end of the
do-whileloop is terminated by a semicolon
11. How to increase the maximum execution time limit in PHP?
We have the following two options to increase the maximum execution time limit
first, We can change the value of given max_execution_time=30 in php.ini file
Second, We can declare the following code at the top of the script
ini_set('max_execution_time', '180'); //180 seconds = 3 minutes
ini_set('max_execution_time', '0'); // for infinite time of execution12. How to use PHP with javascript?
We can’t use PHP code to an external javascript file. because it has .js extension but you know that PHP script can only execute in the file that has .php extension.
But we can use within the inline and internal javascript file like the following a script
<script> <?php $a=10;$b=20; ?> document.write(<?php echo $a+$b;?>); </script>
13. How to display an array in PHP?
We can display the array using print_r().
$arr=['Noor','Sunil','Ayush']; print_r($arr);
14. What is the difference between session_destroy & session_unset?
session_destroy- it can destroy all the registered data of the session.
session_unset- All session variables will be free by declaring it.
15. What is class
Class is a container which contains properties and method.
syntax- class ClassName{}
class Boy{
public $fname="Coding";
public $lname="Status";
public function fullName(){
echo $fname." ".$lname;
}
}16. What is the object?
An object is the instance of a class that is used to access its properties or methods.
It is created from a class such as new ClassName()
class Boy{
public $fname="Coding";
public $lname="Status";
public function fullName(){
echo $fname." ".$lname;
}
}
$obj=new Boy();
$obj->fullName();17. What is the final class?
final class does not allow to create own object but it can be inherited by child classes.
Example –
If we have declared a class with the final keyword, we can’t create an object from that class. but We can access its properties through its child class.
final class Maths(){
public $a=20;
public $b=30;
public function sum(){
echo $a+$b;
}
}
class Cal extends Maths{
public function mul(){
$mult=$this->a*$this->b;
echo $mult;
}
}
$obj=new Cal();
$obj->sum();
$obj->mul();18. What is the difference between $var and $$var
Name of $$var is $vat but Name of $var is var
$$var is the reference variable but $var is the normal variable.
$name="Coding"; $$name="Status"; echo $name; // it returns Coding echo $$name; // It returns Status echo $Coding; // It returns Status
19. What is Regular Expression?
The regular expression is the combination of characters.
It provides the functionality to match the pattern with searching characters
20. What is oops?
Opps is the short form of the object-oriented programming system
It is not a programming language. It’s a concept to make powerful and secure the source code.
Advanced PHP Interview Questions for Experienced
This is the collection of the basic Advanced PHP Interview Questions with answers and examples. It is more necessary for experienced developers. But Beginner developers may prepare these types of questions.
1. Who is the founder of PHP?
2. what are the advantage of PHP?
- PHP is light-weight and fast execution
- PHP is free to use.
- It can run on any operating system like Windows, UNIX, MAC
- It can support many databases like Oracle, MySQL, SQL Server
- PHP can also support OOPS concept
3. In which language PHP was written
PHP Script was written in C & C++
4. Explain 10 string functions.
strlen() Function
It is used to calculate the length of a string
Example – 1
$strlen="I am a string"; echo strlen($strlen);
explode() Function
It creates an array from a string
$expStr="I am a string";
$expArr=explode('',$expStr);
print_r($expArr);implode() Function
It creates a string from an array
$impArr=["I","am","an","array"]; $impStr=implode($impArr); echo $impStr;
str_rev() Function
It can display a string in the opposite direction.
By default, a string seems from left to right. but str_rev reverse it from right to left
$myStr="I am a string"; $strRev=str_rev($myStr); echo $strRev;
str_word_count() Function
It is used to calculate the total number of words of a string.
$myStr="I am a string"; $words=str_word_count($myStr); echo $words;
trim() Function
It removes the whitespaces from both sides of a string.
It can also remove custom characters from both sides of a string
$str = "Coding Status"; echo $str . "<br>"; echo trim($str,"Cus");
str_replace() Function
It is used to replace characters of the string.
$str="Coding Status";
echo str_replace("Coding","Noor",$str);md5() Function
It is used to calculate the md5 hash of a string
$myStr="I am a string"; echo md5($myStr);
strtolower() Function
It is used to display a string into lowercase.
$myStr="I AM A STRING"; echo strtolower($mystr);
strtoupper() Function
It is used to display a string into uppercase
Example
$myStr="I am a string"; echo strtoupper($myStr);
5. Explain 10 array functions.
count() Function
It is used to calculate the total number of elements of an array
$arr=["I","am","a","string"]; echo count($arr);
array_combine() Function
It creates a new array using keys from the first array and values from the second array.
$arr1=array('Name','Age','City');
$arr2=array('Noor',25,'Patna');
$arrComb=array_combine($arr,$arr2);
print_r($arrComb);array_merge() Function
It creates an array by merging elements of two arrays
$arr1=array('Name','Age','City');
$arr2=array('Noor',25,'Patna');
$arrComb=array_merge($arr,$arr2);
print_r($arrComb)array_push() Function
It is used to insert one or more elements into an array
$arr=array("Amit","Sumit","Ravi");
$arrPush=array_push($arr,"Mohan","Radha");
print_r($arrPush);array_pop() Function
It is used to remove the last element of an array
$arr=array("Amit","Sumit","Ravi");
$arrPop=array_pop($arr);
print_r($arrPop);array_revers() Function
It can reverse elements of an array.
$a=array("Amit","Sumit","Ravi");
print_r(array_reverse($a));array_sum() Function
It is used to add elements of an array.
$arr=array(30,20,40); $arrSum=arrar_sum($arr); echo $arrSum
array_product() Function
It is used to multiply elements of an array
$arr=array(30,20,40); $arrMult=array_product($arr); echo $arrMult;
ksort() Function
According to the key, It is used to convert an associative array in ascending order.
$arr=array("Amit"=>"35","Sunil"=>"24","Mohan"=>"18");
ksort($arr);
foreach($arr as $key=>$value)
{
echo "Name: " . $key . ", -Age: " . $value;
echo "<br>";
}krsort() Function
According to the key, It is used to convert an associative array in descending order.
$arr=array("Amit"=>"35","Sunil"=>"24","Mohan"=>"18");
krsort($arr);
foreach($arr as $key=>$value) {
echo "Name: " . $key . ", -Age: " . $value; echo "<br>";
}6. What are the differences between pre & post-increment?
pre-increment
First of all, It increases the value by one then returns then it will return the value.
In the case of pre-increment, a variable begins with a double plus sign like ++$x
$num = 100; echo ++$num; echo "<br>"; echo $num;
post-increment
First of all, It returns then it will increase the value.
In the case of post-increment, a variable ends with a double plus sign like $x++
$num = 100; echo $num++; echo "<br>"; echo $num;
7. What are the differences between pre & post decrement?
pre-decrement
First of all, It decreases the value by one then returns then it will return the value.
In the case of pre-decrement, a variable begins with a double plus sign like –$x
$num = 100; echo --$num; echo "<br>"; echo $num;
post-decrement
First of all, It returns then it will decrease the value.
In the case of post-decrement, a variable ends with a double plus sign like $x–
$num = 100; echo $num--; echo "<br>"; echo $num;
8. What is difference between <> and !==
Not equal <>
In the case of Not Equal, comparison variables must not have the same value to return true.
Suppose that we compare two variables using Not equal.it will return true, if values of both variables are not equal.
$a=20; // integer type
$b="30"; // string type
if($a<>$b)
{
echo "I am true";
}
else
{
echo "I am False";
}Not identical !==
In the case of Not identical, comparison variables must not have the same value as well as the same data type to return true.
Suppose that we compare two variables using Not identical.it will return true, if values of both variables & datatype are not equal.
$a=20; // integer type
$b="30"; // string type
if($a!==$b)
{
echo "I am true";
}
else
{
echo "I am False";
}9. What are PHP filter Extension and its function?
Filter Extension
It used to validate data & remove illegal characters from the data.
It has the following function that is mostly used to validate the data.
filter_var()
It can validate the data and convert in the proper format
Example-1
Validation of an email
$email = "codingstatus@gmail.com";
$checkEmail = filter_var($email, FILTER_SANITIZE_EMAIL);
if (filter_var($checkEmail, FILTER_VALIDATE_EMAIL) === true) {
echo(" valid email address");
} else {
echo("invalid email address");
}Example- 2
validation of a URL
$url = "https://codingstatus.com";
$checkURL = filter_var($url, FILTER_SANITIZE_URL);
if (filter_var($checkURL, FILTER_VALIDATE_URL) === true) {
echo("valid URL");
} else {
echo("Invalid URL");
}Example-3
Validation of a string to remove HTML element
$str = "<h1>I am CodingStatus</h1>"; $removeHTML = filter_var($str, FILTER_SANITIZE_STRING); echo $removeHTML;
10. Explain different New Features of PHP7
Constant arrays using define()
We can use define() to create a constant array
define("coding", [
"PHP",
"HTML",
"Python"
]);
echo coding[0];Scalar type declarations
We can pass arguments to the function with their data type
function bio(string $name,int $age)
{
echo "My name is: ".$name;
echo "<br>";
echo "My age is: ".$age;
}
$name="Noor Khan";
$age=25;
bio($name,$age);
Return type declarations
We can declare the data type of a function to return declared type of value.
function sum($a,$b):int{
return $a+$b;
}
echo sum(30,80);Group use declarations
We can group one or more entities from a common namespace
namespace first{
class A{}
class B{}
class C{}
class D{}
}
namespace{
first\A;
first\B;
first\C;
first\D;
or
// Group declarations
first\{A,B,C,D};
}Null coalescing operator (??)
We can check the value is exist or not null using Null coalescing operator.
Syntax $var= statement1 ?? statement2;
if $var has a value & not null,It will return statement1
echo $name = $_GET["name"] ?? "No value";
Spaceship operator
It is a combination of less than, equal to and greater than, operators.
It is used to compare two values $var1 and $var2 as the following condition
- if $var1 is less than $var2, it will return -1
- When $var1 is equal to $var2, it will return 0
- if $var1 greater than $var2,it will return 1
Example –
$var1 = 99; $var2 = 100; echo ($var1 <=> $var2); // returns -1 because $var1 is less than $var2 echo "<br>"; $var1 = 99; $var2 = 99; echo ($var1 <=> $var2); // returns 0 because values are equal echo "<br>"; $var1 = 100; $var2 = 99; echo ($var1 <=> $var2); // returns 1 because $var1 is greater than $var2
Anonymous classes
We can declare a class without its name that is known as Anonymous class.
$obj=new class(){
function __construct(){
echo "I am an anonymous class";
}
};Closure::call method
It is used to bind an object’s scope to a closure method.
Example –
class A {
private $name = "Noor Khan";
}
// PHP 7+ code, Define
$value = function() {
return $this->name;
};
print($value->call(new A)); // it returns Noor KhanGenerator delegation
It is a function that returns many required values using yield.
A function that contains yield, will be a generator function.
function print_number() {
for ($i = 1; $i <= 5; $i++) {
yield $i;
}
}
$generator = print_number();
foreach ($generator as $value) {
echo "$valuen";
}11. What are the different types of errors?
Php has three types of errors as
- Notice Error
- Warning Error
- Fatal Error
Notice Error
If We access a variable that is not declared. We will generate a notice error;
echo $num;
Warning Error
If We pass the wrong parameter to the function. We will get a warning error and all the script will execute.
Suppose that We pass an unknown file to include(), we will get a warning error.
include(unknown-file.php);
Fetal Error
When we call a function that is not defined. We will get a fatal error and all the script will not execute.
demo();
suppose that We pass an unknown file to require().we will get a fatal error.
require('unkonwn-file.php');12. What are the advantages of OOPS?
- OOPS is a real-world programming concept
- It can hide the information to keep secure the code.
- It allows us to reuse the code.
13. What are the functions of regular expression?
There are five different functions of regular expression
preg_match()preg_match_all()preg_replace()preg_split()preg_grep()preg_quote()
14. Explain different types of array
Indexed Array
It has a numeric index that begins from 0 to a number of declared elements.
$arr1=array('Noor',25,Patna);
or
$arr2=['Noor',25,Patna];
Associative Array
An associative array can have the custom index and its indexes & values are declared with an arrow symbol=>
You can create a custom index in an associative array and Custom index may be a number or string.
$arr=array("Name"=>"Noor","Age"=>25,"City"=>"Patna");
or
$arr1=["Name"=>"Noor","Age"=>25,"City"=>"Patna"];Multi-dimensional Array
It is a nested array that contains one or more arrays.
$multiArr=array(
array('25',30,40),
array('Noor','Sunil','Ayush'),
array('Patna','Delhi','Noida')
);PHP Coding Questions for Interview
These types of PHP Interview Questions are coding based questions for the written test.
These questions more necessary for experienced developers and freshers can prepare as well
These questions will clear your coding concept and learn you to develop logic.
After preparing the javascript coding question, you will able to solve any level of questions.
Generally, interviewers will ask questions based on the concept of these listed questions in the written test. Therefore you must do practical of these questions again and again.
1. What is the data type of $x=34.2
$x=34.2; echo gettype($x); // output- double
Suggestion
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Amazing, Very nice collections of questions & Answers.