How do you know whether the headers are sent or not?

We have a function headers_sent(). This function is used to check whether the headers are already sent.

What is the difference between method get and method post?

The first difference is, method get is faster in performance than post. Because, by using post method the data posted is encrypted to cipher data and sent to the server. Where in get the encryption does not happens and it is faster.
    Get method can carry limited amount of data and it is less than post method.
    Post method is secure than get as the data submitted is not visible to the real world. Where as in the get method some one may see the data submitted in the URL bar.
    Using post method We can submit the data to the server only with the help of an HTML form. Where as a get method can send the data to server with a form and also with a HTML hyperlink.

What is difference between include() function and require() function?

Both the functions are used to include a PHP file in other PHP file. Generally if we have a block of source code usefull in multiple instances, then we place the block of source code in one file and will include the file in other files. The difference between include() and require() function are as follows:
    (i) If the file path mentioned with the include function is not found then it shows a warning message and continues the execution of the script. Where as require function results a fatal error and stops the execution of the script.
    (ii) The second difference is include function is faster in execution than require function. Because with the require function the parser will check whether the file exists or not. Where as the include function does not bothere about the file is there or not.

How many types of comments are there in PHP?

There are two types of comments in PHP. They are

1. One Line comments (// or #)
2. Multiple Line comments (/* */)

The "one-line" comment styles only comment to the end of the line or the current block of PHP code, whichever comes first.
Eg:

      

     <?

      // echo 'Your code upto end of the line'; 

     ?>

     <?

     # echo 'Your code upto end of the line';  

     ?> 

Multiple Line comments (/* */) are used to comment a large block of PHP code.
Ex: <?

 /*
    echo 'This is a test';

    echo 'This is a test line2';

       echo 'This is a test line 3';
 */
?>

What is the difference between displaying a string in single quotes and double quotes in PHP?

1) With Single Quotes the performance is faster than double quotes because the PHP parser does not checks for any variables or special characters. Whatever is there it will display that.
2) With double quotes the parser will search for the variables embedded in the string.
3) Performance wise it is always better to use single quotes. And we can use the concatenation between the strings and the variables.
4) Double quotes recognizes the new line charactes like '\n','\t' etc.., where as single quotes does not.

Top 10 PHP MVC frameworks

A good framework is easy to learn, simple to use, intuitive to work with, easy to extend or to modify, rapid to build (maintain) applications with and of course stable.

Having said that, here is my top 10 PHP MVC Frameworks:

10- Ambivalence: A Java-Maverick Port
9- WACT: Web Application Component Toolkit
8- Achievo: A good RAD framework
7- Phrame: A Java-Struts port
6- Studs: A Java-Struts port to PHP
5- Prado: The winner of Zend coding contest
4- PHPOnTrax: a Rails port - PHP5 Only
3- CakePHP: Inspired by Rails PHP4/5
2- Mojavi: The first MVC framework I fell in love with

and the winner is:

1- Symfony: Based on Mojavi and inspired by Rails

This list is based on my personal tests and use. I have tested and played with many others, but I think these are the best frameworks out there.
- The first framework I fell in love with was Mojavi because of its elegant way to implement the MVC model.
- Symfony corrected some problems in Mojavi and improved it by taking the good sides of RubyOnRails and Propel.
- CakePHP is very promising, the only problem - really, I don't know if it is a problem - is: the development process is very slow.

Redirecting a Web Page Using a 301 Redirect with HTACCESS file

Below is the steps involved in redirecting a web page usinh HTACCESS file.
Know about .htaccess file
When a visitor/spider requests a web page, your web serverchecks for a .htaccess file. The .htaccess file containsspecific instructions for certain requests, includingsecurity, redirection issues and how to handle certainerrors.
Know about 301 redirect
301 redirect is the best method to preserve your currentsearch engine rankings when redirecting web pages or a website. The code "301" is interpreted as "moved permanently".After the code, the URL of the missing or renamed page isnoted, followed by a space, then followed by the newlocation or file name. You implement the 301 redirect bycreating a .htaccess file.
How to implement the 301 Redirect
1. To create a .htaccess file, open notepad, name and savethe file as .htaccess (there is no extension).
2. If you already have a .htaccess file on your server,download it to your desktop for editing.
3. Place this code in your .htaccess file:redirect 301 /old/old.htm http://www.you.com/new.htm
4. If the .htaccess file already has lines of code in it,skip a line, then add the above code.
5. Save the .htaccess file
6. Upload this file to the root folder of your server.
7. Test it by typing in the old address to the page you'vechanged. You should be immediately taken to the newlocation.
Notes: Don't add "http://www" to the first part of thestatement - place the path from the top level of your siteto the page. Also ensure that you leave a single spacebetween these elements:
          redirect 301 (the instruction that the page has moved)

          /old/old.htm (the original folder path and file name)

          http://www.you.com/new.htm (new path and file name)

When the search engines spider your site again they willfollow the rule you have created in your .htaccess file.The search engine spider doesn't actually read the .htaccess file, but recognizes the response from the server as valid.
During the next update, the old file name and path will bedropped and replaced with the new one. Sometimes you maysee alternating old/new file names during the transitionperiod, plus some fluctuations in rankings. According toGoogle it will take 6-8 weeks to see the changes reflectedon your pages.
Other ways to implement the 301 redirect:
1. To redirect ALL files on your domain use this in your.htaccess file if you are on a unix web server:
          redirectMatch 301 ^(.*)$ http://www.domain.com

          redirectMatch permanent ^(.*)$ http://www.domain.com

You can also use one of these in your .htaccess file:
          redirect 301 /index.html http://www.domain.com/index.html

          redirect permanent /index.html http://www.domain.com/index.html

          redirectpermanent /index.html http://www.domain.com/index.html

This will redirect "index.html" to another domain using a301-Moved permanently redirect.
2. If you need to redirect http://mysite.com tohttp://www.mysite.com and you've got mod_rewrite enabled onyour server you can put this in your .htaccess file:
          Options +FollowSymLinks
          RewriteEngine on
          RewriteCond %{HTTP_HOST} ^example\.com
          RewriteRule ^(.*)$ http://www.example.com/$1 [R=permanent,L]
or this:
          Options +FollowSymLinks

          RewriteEngine

          OnRewriteCond %{HTTP_HOST} ^domain\.com$ [NC]

          RewriteRule ^(.*)$ http://www.domain.com/$1 [R=301,L]

Tip: Use your full URL (ie http://www.domain.com) whenobtaining incoming links to your site. Also use your fullURL for the internal linking of your site.
3. If you want to redirect your .htm pages to .php pagesandd you've got mod_rewrite enabled on your server you canput this in your .htaccess file:
          RewriteEngine on

          RewriteBase /

          RewriteRule (.*).htm$ /$1.php

4. If you wish to redirect your .html or .htm pages to.shtml pages because you are using Server Side Includes(SSI) add this code to your .htaccess file:
          AddType text/html .shtml

          AddHandler server-parsed .shtml .html .htm

Options Indexes FollowSymLinks Includes
DirectoryIndex index.shtml index.html