Basics PHP Questions & Answer

What is Output Buffering?

The Output Control functions allow you to control when output is sent from the script. This can be useful in several different situations, especially if you need to send headers to the browser after your script has begun outputting data. The Output Control functions do not affect headers sent using header() or setcookie(), only functions such as echo and data between blocks of PHP code.

What's the difference between htmlentities() and htmlspecialchars()?

Htmlspecialchars only takes care of <, >, single quote ', double quote " and ampersand. Htmlentities translates all occurrences of character sequences that have different meaning in HTML.

What is MIME?

MIME - Multi-purpose Internet Mail Extensions.
MIME types represents a standard way of classifying file types over Internet.
Web servers and browsers have a list of MIME types, which facilitates files transfer of the same type in the same way, irrespective of operating system they are working in.
A MIME type has two parts: a type and a subtype. They are separated by a slash (/).
MIME type for Microsoft Word files is application and the subtype is msword, i.e. application/msword.

What does type casting mean in PHP? Explain with an example?

PHP automatically store the data and interprets according to itself. Type casting is a way to assign the variable according to your need and requirement and not allowing PHP to assign it automatically. To specify the type, it can be used like:
$newint = (int) $var1;
$newfloat = (float) $var1;
$newstring = (string) $var1;
The value in the variable on the right side of the equal sign is stored in the variable on the left side as the specified type.

What is the difference between Session and Cookie?

The main difference between sessions and cookies is that sessions are stored on the server, and cookies are stored on the user's computers in the text file format. Cookies can not hold multiple variables,But Session can hold multiple variables.We can set expiry for a cookie,The session only remains active as long as the browser is open.Users do not have access to the data you stored in Session,Since it is stored in the server.Session is mainly used for login/logout purpose while cookies using for user activity tracking.

How to set cookies in PHP?

setcookie(name, value, expire, path, domain, secure, httponly);

name     Required. Specifies the name of the cookie

value     Optional.  Specifies the value of the cookie

expire    Optional.  Specifies when the cookie expires. The value: time()+86400*30, will set the cookie to expire in 30 days. If this parameter is omitted or set to 0, the cookie will expire at the end of the session (when the browser closes). Default is 0

path     Optional. Specifies the server path of the cookie. If set to "/", the cookie will be available within the entire domain. If set to "/php/", the cookie will only be available within the php directory and all sub-directories of php. The default value is the current directory that the cookie is being set in

domain   Optional. Specifies the domain name of the cookie. To make the cookie available on all subdomains of example.com, set domain to "example.com". Setting it to www.example.com will make the cookie only available in the www subdomain

secure     Optional. Specifies whether or not the cookie should only be transmitted over a secure HTTPS connection. TRUE indicates that the cookie will only be set if a secure connection exists. Default is FALSE

httponly   Optional. If set to TRUE the cookie will be accessible only through the HTTP protocol (the cookie will not be accessible by scripting languages). This setting can help to reduce identity theft through XSS attacks. Default is FALSE.