Interview Questions on PHP set-1

What's PHP ?

 
The PHP Hypertext Preprocessor is a programming language that allows web developers to create dynamic content that interacts with databases. PHP is basically used for developing web based software applications.

What Is a Session?
 

A session is a logical object created by the PHP engine to allow you to preserve data across subsequent HTTP requests.

There is only one session object available to your PHP scripts at any time. Data saved to the session by a script can be retrieved by the same script or another script when requested from the same visitor.

Sessions are commonly used to store temporary data to allow multiple PHP pages to offer a complete functional transaction for the same visitor.

What is meant by PEAR in php?
 

Answer1:
PEAR is the next revolution in PHP. This repository is bringing higher level programming to PHP. PEAR is a framework and distribution system for reusable PHP components. It eases installation by bringing an automated wizard, and packing the strength and experience of PHP users into a nicely organised OOP library. PEAR also provides a command-line interface that can be used to automatically install "packages"

Answer2:
PEAR is short for "PHP Extension and Application Repository" and is pronounced just like the fruit. The purpose of PEAR is to provide:
A structured library of open-sourced code for PHP users
A system for code distribution and package maintenance
A standard style for code written in PHP
The PHP Foundation Classes (PFC),
The PHP Extension Community Library (PECL),
A web site, mailing lists and download mirrors to support the PHP/PEAR community
PEAR is a community-driven project with the PEAR Group as the governing body. The project has been founded by Stig S. Bakken in 1999 and quite a lot of people have joined the project since then.

How can we know the number of days between two given dates using PHP?
 

Simple arithmetic:

$date1 = date('Y-m-d');
$date2 = '2006-07-01';
$days = (strtotime() - strtotime()) / (60 * 60 * 24);
echo "Number of days since '2006-07-01': $days";

What is the difference between $message and $$message?
 

Anwser 1:
$message is a simple variable whereas $$message is a reference variable.

Example:         $user = 'bob'    is equivalent to
$holder = 'user';
$$holder = 'bob';

Anwser 2:They are both variables. But $message is a variable with a fixed name. $$message is a variable whose name is stored in $message. For example, if $message contains "var", $$message is the same as $var.

What Is a Persistent Cookie?
 

A persistent cookie is a cookie which is stored in a cookie file permanently on the browser's computer. By default, cookies are created as temporary cookies which stored only in the browser's memory. When the browser is closed, temporary cookies will be erased. You should decide when to use temporary cookies and when to use persistent cookies based on their differences:

• Temporary cookies can not be used for tracking long-term information.
• Persistent cookies can be used for tracking long-term information.
• Temporary cookies are safer because no programs other than the browser can access them.
• Persistent cookies are less secure because users can open cookie files see the cookie values.

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

The output is displayed directly to the browser.  

How do you define a constant?
 

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

What are the differences between require and include, include_once?
 

Anwser 1:
require_once() and include_once() are both the functions to include and evaluate the specified file only once. If the specified file is included previous to the present call occurrence, it will not be done again.

But require() and include() will do it as many times they are asked to do.

Anwser 2:
The include_once() statement includes and evaluates the specified file during the execution of the script. This is a behavior similar to the include() statement, with the only difference being that if the code from a file has already been included, it will not be included again. The major difference between include() and require() is that in failure include() produces a warning message whereas require() produces a fatal errors.

Anwser 3:
All three are used to an include file into the current page.
If the file is not present, require(), calls a fatal error, while in include() does not.
The include_once() statement includes and evaluates the specified file during the execution of the script. This is a behavior similar to the include() statement, with the only difference being that if the code from a file has already been included, it will not be included again. It des not call a fatal error if file not exists. require_once() does the same as include_once(), but it calls a fatal error if file not exists.

Anwser 4:
File will not be included more than once. If we want to include a file once only and further calling of the file will be ignored then we have to use the PHP function include_once(). This will prevent problems with function redefinitions, variable value reassignments, etc.

What is the difference between mysql_fetch_object and mysql_fetch_array?
 

MySQL fetch object will collect first single matching record where mysql_fetch_array will collect all matching records from the table in an array

How can I execute a PHP script using command line?
 

Just run the PHP CLI (Command Line Interface) program and provide the PHP script file name as the command line argument. For example, "php myScript.php", assuming "php" is the command to invoke the CLI program.
Be aware that if your PHP script was written for the Web CGI interface, it may not execute properly in command line environment.

I am trying to assign a variable the value of 012ot3, 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.

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.

What are the different tables present in MySQL? Which type of table is generated when we are creating a table in the following syntax: create table employee(eno int(2),ename varchar(10))?
 

Total 5 types of tables we can create
1. MyISAM
2. Heap
3. Merge
4. INNO DB
5. ISAM
MyISAM is the default storage engine as of MySQL 3.23. When you fire the above create query MySQL will create a MyISAM table.

Interview Questions on PHP set-2

How To Create a Table?
 

If you want to create a table, you can run the CREATE TABLE statement as shown in the following sample script:

<?php
include "mysql_connection.php";

$sql = "CREATE TABLE Tech_links ("
. " id INTEGER NOT NULL"
. ", url VARCHAR(80) NOT NULL"
. ", notes VARCHAR(1024)"
. ", counts INTEGER"
. ", time TIMESTAMP DEFAULT sysdate()"
. ")";
if (mysql_query($sql, $con)) {
print("Table Tech_links created.\n");
} else {
print("Table creation failed.\n");
}
mysql_close($con);
?>

Remember that mysql_query() returns TRUE/FALSE on CREATE statements. If you run this script, you will get something like this:
Table Tech_links created.

How can we encrypt the username and password using PHP?

Answer1
You can encrypt a password with the following Mysql>SET PASSWORD=PASSWORD("Password");

Answer2
You can use the MySQL PASSWORD() function to encrypt username and password. For example,
INSERT into user (password, ...) VALUES (PASSWORD($password?)), ...);

How do you pass a variable by value?

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

What is the functionality of the functions STRSTR() and STRISTR()?

string strstr ( string haystack, string needle ) returns part of haystack string from the first occurrence of needle to the end of haystack. This function is case-sensitive.

stristr() is idential to strstr() except that it is case insensitive.

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.

How can we send mail using JavaScript?

No. There is no way to send emails directly using JavaScript.

But you can use JavaScript to execute a client side email program send the email using the "mailto" code. Here is an example:

function myfunction(form)
{
tdata=document.myform.tbox1.value;
location="mailto:mailid@domain.com?subject=...";
return true;
}

What is the functionality of the function strstr and stristr?

strstr() returns part of a given string from the first occurrence of a given substring to the end of the string. For example: strstr("user@example.com","@") will return "@example.com".

stristr() is idential to strstr() except that it is case insensitive.

What is the difference between ereg_replace() and eregi_replace()?

eregi_replace() function is identical to ereg_replace() except that it ignores case distinction when matching alphabetic characters.

How do I find out the number of parameters passed into function9. ?

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

What is the purpose of the following files having extensions: frm, myd, and myi? What these files contain?

In MySQL, the default table type is MyISAM.
Each MyISAM table is stored on disk in three files. The files have names that begin with the table name and have an extension to indicate the file type.

The '.frm' file stores the table definition.
The data file has a '.MYD' (MYData) extension.
The index file has a '.MYI' (MYIndex) extension,

If the variable $a is equal to 5 and variable $b is equal to character a, what?s the value of $$b?

100, it?s a reference to existing variable.

How To Protect Special Characters in Query String?

If you want to include special characters like spaces in the query string, you need to protect them by applying the urlencode() translation function. The script below shows how to use urlencode():

<?php
print("<html>");
print("<p>Please click the links below"
." to submit comments about TECHPreparation.com:</p>");
$comment = 'I want to say: "It\'s a good site! :->"';
$comment = urlencode($comment);
print("<p>"
."<a href=\"processing_forms.php?name=Guest&comment=$comment\">"
."It's an excellent site!</a></p>");
$comment = 'This visitor said: "It\'s an average site! :-("';
$comment = urlencode($comment);
print("<p>"
.'<a href="processing_forms.php?'.$comment.'">'
."It's an average site.</a></p>");
print("</html>");
?>

Are objects passed by value or by reference?

Everything is passed by value.

What are the differences between DROP a table and TRUNCATE a table?

DROP TABLE table_name - This will delete the table and its data.

TRUNCATE TABLE table_name - This will delete the data of the table, but not the table definition.

How do you call a constructor for a parent class?

parent::constructor($value)

WHAT ARE THE DIFFERENT TYPES OF ERRORS IN PHP?

Here are three basic types of runtime errors in PHP:

1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script - for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all - although you can change this default behavior.

2. Warnings: These are more serious errors - for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.

3. Fatal errors: These are critical errors - for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP's default behavior is to display them to the user when they take place.

Internally, these variations are represented by twelve different error types

What?s the special meaning of __sleep and __wakeup?

__sleep returns the array of all the variables than need to be saved, while __wakeup retrieves them.

How can we submit a form without a submit button?

If you don't want to use the Submit button to submit a form, you can use normal hyper links to submit a form. But you need to use some JavaScript code in the URL of the link. For example:

<a href="javascript: document.myform.submit();">Submit Me</a>

PHP Interview Tips and General Questions

So you’ve been slinging resumes for a while and now you have an interview for an awesome PHP job. While part of the interview will be the typical job interview, you should also be prepared for a technical interview. Technical interviews are often given to determine how well you truly know the technologies with which you’ll be working. There are numerous books and articles to help you prepare for the job interview portion but very little has been said on preparing for a PHP technical interview. General PHP Questions The first type of questions you’ll be asking in a PHP interview will be general questions about PHP itself. Typically, technical interviewers like to start with easy general questions about PHP such as special output tags, how to pass parameters, how to define constants and how to define variables. Depending on the interviewers own technical background, they may progress to questions on more advanced usage such as the object oriented features of PHP. Spend some time prior to your interview to brush up somewhat on the basics of the language. Sample Questions Q: What’s a PHP Session? A: PHP Session is an object created by the PHP engine that persists data between HTTP requests Q: What are tags used for? A: They allow to output the result of the expression between the tags directly to the browser response. Q: How do you define a constant? A: define(“CONSTANT_NAME”, “constant value”); Q: How would you get the number of parameters passed into a method? A: use the fun_num_args() call within the method MySQL If you are having a PHP interview, it is pretty likely that you are interviewing for some type of web development job. That means it is almost certain that MySQL will be used. You should expect to be asked some questions about accessing MySQL from PHP in your interview. These questions don’t always get very deep. If you can describe how to connect to a database and execute a simple select query, you will likely pass your PHP interview. Sample Questions Q: How would you create a MySQL database from PHP? A: mysql_query(“CREATE DATABASE db_name” connector); Q: How would you see all tables in a database? A: mysql> use db_name; show tables; Q: How do you change a password for a given user via mysqladmin utility? A: mysqladmin -u root -p password “newpassword” PHP Frameworks Larger companies and web development shops are increasingly moving towards frameworks in their development. If you want to pass a PHP interview, you should at least know what a framework is, what the most popular frameworks are and know a little about some of their features. Check out the web site for CakePHP for some simple documentation that will give you an idea of the features and uses of a PHP framework. Sample Questions Q: What are the advantages of using a PHP framework? A: Code reuse, multitude of service APIs, code modularity with Model-View-Controller (MVC) pattern, community support, and multitude of plugins. Best Practices The final category of questions in a PHP interview typically covers best practices. You may be asked about architectural concepts such as scaling an application in PHP. You can easily find a number of useful articles on the subject. You may also be asked about security in PHP. You should be able to describe how to prevent common web based attacks such as SQL injection or cross site scripting from PHP. Short-n-Sweet During the interview, you want to appear relaxed and confident in your knowledge. Take a moment to really listen to the question before you answer. When you do answer, provide the shortest answer possible. You don’t need a lengthy explanation and you do not want to appear to be rambling. Simply answer the question as succinctly as possible. Passing a PHP interview is really quite easy if you have a good grasp of the language and take the time to review material that an interviewer is likely to ask about. Know the basics of the language syntax. Don’t limit your review to PHP though. Many PHP interviews WILL include questions about frameworks, security, MySQL and architecture. Relax and answer the question as succinctly as you can. Good luck!

Resume for fresher On PHP

NARESH CHIRUVELLA                                                     Mobile: +91-XXXXXXXXXX                                                                                    Email: ch.v.naresh@gmail.com Objective: To strive for Excellence in the field of design with dedication, focus, proactive approach, positive attitude and passion and to utilize my knowledge and skills in the best possible way for the fulfillment of organizational goals. EDUCATION                                       Degree institute university Year percentage class    B.Tech (Electronics) Rao & Naidu Engineering College, Ongole J.N.T.U, Hyderabad 2010 65% First Intermediate (M.P.C) Sir Raman junior college, Kavali B.O.I, A.P 2006 67.5% First X class R.K.Jr college SSC, A.P 2004 75% Distinction Technical SKILLS: Operating System Platforms :        Windows XP Programming Languages      :        PHP, C, C++ Database                          :        PL/SQL, MySQL and Sql Server Internet Technologies          :        HTML, JAVASCRIPT Packages                          :        MS-Office ACADEMIC PROJECT: Title              :  JPEG IMAGE COMPRESSION Duration       :  25th December 2009 to 20th April 2010 Description:                                   Images and data are stored in semiconductor memories. Images occupy a large amount of memory space. We can reduce the memory space occupied by images using the technique “IMAGE COMPRESSION”.                             Image compression means reducing the number of bits occupied by each semi part of the image with good clarity. Image compression is adopted by number of coding Techniques. In this Project we have to implement “HUFFMAN CODING”. PERSONAL STRENGTHS: v  An ability to learn quickly and adapt to circumstances and keep on improving. v  Ability to work in a team. v  Ability to deal with people diplomatically. v  Willingness to learn. v  Readily accept challenges. v  A fast learner and a great sense of grasping methods immediately. v  Extremely helpful towards co-workers, customers and very patient. v  Extremely flexible with work schedules and able to adjust availability according to work requirements. Personal details:                          Date of birth : 10TH MAY 1988 Father Name : OBAIAH CH Nationality                  : Indian Marital Status : SINGLE Languages known : English ,Telugu & Hindi Declaration:                  I hereby declare that the above-mentioned information is correct up to my knowledge.