PHP Interview Questions and Answers

1.   What does a special set of tags <?= and ?> do in PHP?

The output is displayed directly to the browser.

2.   What’s the difference between include and require?

It’s how they handle failures. If the file is not found by require(), it will cause a fatal error and halt the execution of the script. If the file is not found by include(), a warning will be issued, but execution will continue.

3.   I am trying to assign a variable the value of 0123, but it keeps coming up with a different number, what’s the problem?

PHP Interpreter treats numbers beginning with 0 as octal. Look at the similar PHP interview questions for more numeric problems.

4.   Would I use print "$a dollars" or "{$a} dollars" to print out the amount of dollars in this example?

In this example it wouldn’t matter, since the variable is all by itself, but if you were to print something like "{$a},000,000 mln dollars", then you definitely need to use the braces.

5.   How do you define a constant?

Via define() directive, like define ("MYCONSTANT", 100);

6.   How do you pass a variable by value?

Just like in C++, put an ampersand in front of it, like $a = &$b

7.   Will comparison of string "10" and integer 11 work in PHP?

Yes, internally PHP will cast everything to the integer type, so numbers 10 and 11 will be compared.

8.   When are you supposed to use endif to end the conditional statement?

When the original if was followed by : and then the code block without braces.

9.   Explain the ternary conditional operator in PHP?

Expression preceding the ? is evaluated, if it’s true, then the expression preceding the : is executed, otherwise, the expression following : is executed.

10.                How do I find out the number of parameters passed into function?

func_num_args() function returns the number of parameters passed in.

PHP OOPS Interview Questions & Answers

1) Explain what is object oriented programming language?

Object oriented programming language allows concepts such as modularity, encapsulation, polymorphism and inheritance.  Objects are said to be the most important part of object oriented language. Concept revolves around making simulation programs around an object. Organize a program around its data (object)& set well define interface to that data. i.e. objects and a set of well defined interfaces to that data. OOP is the common abbreviation for Object-Oriented Programming.  OOps have many properties such as DataHiding,Inheritence,Data Absraction,Data Encapsulation and many more.

2) Name some languages which have object oriented language and characteristics?

Some of the languages which have object oriented languages present in them are ABAP, ECMA Script, C++, Perl, LISP, C#, Tcl, VB, Ruby, Python, PHP, etc. Popularity of these languages has increased considerably as they can solve complex problems with ease.

3) Explain about UML?

UML or unified modeling language is regarded to implement complete specifications and features of object oriented language. Abstract design can be implemented in object oriented programming languages. It lacks implementation of polymorphism on message arguments which is a OOPs feature.

4) Explain the meaning of object in object oriented programming?

Languages which are called as object oriented almost implement everything in them as objects such as punctuations, characters, prototypes, classes, modules, blocks, etc. They were designed to facilitate and implement object oriented methods.

5) Explain about message passing in object oriented programming?

Message passing is a method by which an object sends data to another object or requests other object to invoke method. This is also known as interfacing. It acts like a messenger from one object to other object to convey specific instructions.

6) State about Java and its relation to Object oriented programming?

Java is widely used and its share is increasing considerably which is partly due to its close resemblance to object oriented languages such as C++. Code written in Java can be transported to many different platforms without changing it. It implements virtual machine.

7) What are the problems faced by the developer using object oriented programming language?

These are some of the problems faced by the developer using object oriented language they are: -

a) Object oriented uses design patterns which can be referred to as anything in general.

b) Repeatable solution to a problem can cause concern and disagreements and it is one of the major problems in software design.

8 ) State some of the advantages of object oriented programming?

Some of the advantages of object oriented programming are as follows: -

a) A clear modular structure can be obtained which can be used as a prototype and it will not reveal the mechanism behind the design. It does have a clear interface.

b) Ease of maintenance and modification to the existing objects can be done with ease.

c) A good framework is provided which facilitates in creating rich GUI applications.

9 ) Explain about inheritance in OOPS?

Objects in one class can acquire properties of the objects in other classes by way of inheritance. Reusability which is a major factor is provided in object oriented programming which adds features to a class without modifying it. New class can be obtained from a class which is already present.

10) Explain about the relationship between object oriented programming and databases?

Object oriented programming and relational database programming are almost similar in software engineering. RDBMS will not store objects directly and that’s where object oriented programming comes into play. Object relational mapping is one such solution.

11) Explain about a class in OOP?

In Object oriented programming usage of class often occurs. A class defines the characteristics of an object and its behaviors. This defines the nature and functioning of a specified object to which it is assigned. Code for a class should be encapsulated.

12) Explain the usage of encapsulation?

Encapsulation specifies the different classes which can use the members of an object. The main goal of encapsulation is to provide an interface to clients which decrease the dependency on those features and parts which are likely to change in future. This facilitates easy changes to the code and features.

13) Explain about abstraction?

Abstraction can also be achieved through composition. It solves a complex problem by defining only those classes which are relevant to the problem and not involving the whole complex code into play.

14) Explain what a method is?

A method will affect only a particular object to which it is specified. Methods are verbs meaning they define actions which a particular object will perform. It also defines various other characteristics of a particular object.

15) Name the different Creational patterns in OO design?

There are three patterns of design out of which Creational patterns play an important role the various patterns described underneath this are: -

a) Factory pattern

b) Single ton pattern

c) Prototype pattern

d) Abstract factory pattern

e) Builder pattern

16) Explain about realistic modeling?

As we live in a world of objects, it logically follows that the object oriented approach models the real world accurately. The object oriented approach allows you to identify entities as objects having attributes and behavior.

17) Explain about the analysis phase?

The anlaysis or the object oriented analysis phase considers the system as a solution to a problem in its environment or domain. Developer concentrates on obtaining as much information as possible about the problem. Critical requirements needs to be identified.