PHP Interview Questions & Answers

PHP Interview Questions & Answers
  1. What's Php?

    Answer :

    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.

  2. What Is A Session?

    Answer :

    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.

  3. What Is Meant By Pear In Php?

    Answer :

    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".

  4. How Can We Know The Number Of Days Between Two Given Dates Using Php?

    Answer :

    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";

  5. How Can We Repair A Mysql Table?

    Answer :

    The syntex for repairing a mysql table is:

    REPAIR TABLE tablename
    REPAIR TABLE tablename QUICK

    This command will repair the table specified.
    If QUICK is given, MySQL will do a repair of only the index tree.
    If EXTENDED is given, it will create index row by row.

  6. What Is The Difference Between $message And $$message?

    Answer :

    $message is a simple variable whereas $$message is a variable's variable,which means
    value of the variable. Example:
    $user = 'bob'

    is equivalent to

    $message = 'user';
    $$message = 'bob';

  7. What Is A Persistent Cookie?

    Answer :

    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.

  8. How Do You Define A Constant?

    Answer :

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

  9. What Are The Differences Between Require And Include, Include_once?

    Answer :

    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.

  10. What Is Meant By Urlencode And Urldecode?

    Answer :

    urlencode() returns the URL encoded version of the given string. URL coding converts special characters into % signs followed by two hex digits. For example: urlencode("10.00%") will return "10%2E00%25". URL encoded strings are safe to be used as part of URLs.
    urldecode() returns the URL decoded version of the given string.

  11. How To Get The Uploaded File Information In The Receiving Script?

    Answer :

    Once the Web server received the uploaded file, it will call the PHP script specified in the form action attribute to process them. This receiving PHP script can get the uploaded file information through the predefined array called $_FILES. Uploaded file information is organized in $_FILES as a two-dimensional array as:

    • $_FILES[$fieldName]['name'] - The Original file name on the browser system.
    •  $_FILES[$fieldName]['type'] - The file type determined by the browser.
    •  $_FILES[$fieldName]['size'] - The Number of bytes of the file content.
    •  $_FILES[$fieldName]['tmp_name'] - The temporary filename of the file in which
      the uploaded file was stored on the server.
    •  $_FILES[$fieldName]['error'] - The error code associated with this file upload.
      The $fieldName is the name used in the .

  12. What Is The Difference Between Mysql_fetch_object And Mysql_fetch_array?

    Answer :

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

  13. How Can I Execute A Php Script Using Command Line?

    Answer :

    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.

  14. I Am Trying To Assign A Variable The Value Of 0123, But It Keeps Coming Up With A Different Number, What's The Problem?

    Answer :

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

  15. Would I Use Print "$a Dollars" Or "{$a} Dollars" To Print Out The Amount Of Dollars In This Example?

    Answer :

    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.

  16. 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))?

    Answer :

    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.

  17. How To Create A Table?

    Answer :

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

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

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

  18. How Can We Encrypt The Username And Password Using Php?

    Answer :

    You can encrypt a password with the following Mysql>SET

  19. How Do You Pass A Variable By Value?

    Answer :

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

  20. What Is The Functionality Of The Functions Strstr() And Stristr()?

    Answer :

    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.

An Introduction To Php The Origins Of Php What Makes Php Better Than Its Alternatives Interfaces To External Systems How Php Works With The Web Server Hardware And Software Requirements Installation On Apache For Unix Installation On Iis For Windows Nt Editing Scripts Algorithms In Php What A Php Script Looks Like Saving Data For Later Receiving User Input Choosing Between Alternatives Repeating Code Variables, Operators, And Expressions Identifiers Php Data Types Variable Creation And Scope Assigning Values To Variables In Php Retrieving Values Freeing Memory Php Constants Php Operators Logical And Relational Operators Bitwise Operators Miscellaneous Operators Assignment Operators What Are Expressions? Control Statements True And False The If Statement The ? Operator The Switch Statement Loops The While Statement The Break Statement The Continue Statement The Do...while Statement The For Statement The Foreach Statement Exit, Die, And Return Evaluation Of Boolean Expressions Functions Declaring A Function The Return Statement Scope And The Global Statement Arguments Recursion In Php Dynamic Function Calls Arrays Single-dimensional Arrays Indexing Arrays Initializing Arrays Multidimensional Arrays Casting Arrays Referencing Arrays Inside Strings Classes And Objects Defining A Class Creating An Object Accessing Properties And Methods I/o And Disk Access Http Connections Writing To The Browser Output Buffering Environment Variables Getting Input From Forms Cookies With Php File Uploads Put Method Requests Reading And Writing To Files Sessions The Include And Require Functions I/o Functions Sending Text To The Browser Output Buffering Commands Files Compressed File Functions Posix Php Debugging Session Handling Shell Commands Http Headers Network I/o Ftp Data Functions Data Types, Constants, And Variables Php Arrays Hashing Strings In Php Encoding And Decoding Encryption Of Php Regular Expressions In Php Perl-compatible Regular Expressions Mathematical Functions Common Math Random Numbers Arbitrary-precision Numbers Time, Date, And Configuration Functions Time And Date Alternative Calendars Configuration Image Functions Analyzing Images Creating Jpeg, Png, And Wbmp Images Database Functions Dbase Dbm-style Database Abstraction Filepro Informix Odbc Oracle Sybase Mysql Msql Inter Base Postgres Parsing And String Evaluation Tokenizing Strtok Function: Regular Expressions Defining Regular Expressions Using Regular Expressions In Php Scripts Database Integration Building Html Tables From Sql Queries Tracking Visitors With Session Identifiers Storing Content In A Database Database Abstraction Layers Miscellaneous Functions Apache Aspell Com Gettext Imap Java Ldap Semaphores Shared Memory Snmp Wddx Xml Expat Library Sorting Searching And Random Numbers Sorting Bubble Sort Quicksort Built-in Sorting Functions Sorting With A Comparison Function Searching In Php Script Indexing Random Numbers In Php Random Identifiers Choosing Banner Ads Network Http Authentication Controlling Browser Cache Setting Document Type Email With Attachments Verifying An Email Address Generating Graphics Dynamic Buttons Generating Graphs On The Fly Pie Charts Bar Graphs Stretching Single-pixel Images Integration With Html Sprinkling Php Within An Html Document Using Php To Output All Html Separating Html From Php Creating Select Fields Passing Arrays In Forms Design Writing Requirements Specifications Writing Design Documents Using Cvs Modularization Using Include Freeenergy Fasttemplate Midgard Ariadne Preserving State And Providing Security Cloaking Urls Friendly To Search Engines Running A Script Regularly Efficiency And Debugging Measuring Performance Fetching Database Query Results When To Store Content In A Database In-line Debugging Remote Debugging Simulating Http Connections Php Interview Questions Php Practice Tests