PHP Questions

User names and passwords in PHP can be encrypted using md5 function.

MD5 function calculates the md5 hash of a string. It is basically used for encryption. It is also used for digital signature applications, where a large file must be "compressed" in a secure manner.

Example:

Md5($str);

Crypt() function can also be used to encrypt a string,. It used MD5, DES or blow fish algorithms for encryption.

Syntax:

Crypt(str, salt)

Salt is an optional parameter used to increase the number of characters encoded, to make the encoding more secure

sort() , rsort(), asort()
ksort()   , usort()
arsort()  , uksort()
natsort() , natcasesort()
array_multisort()

By default the maximum size is 2MB. and we can change the following
setup at php.iniupload_max_filesize = 2M

Htmlentities() converts all applicable characters to HTML entities. While htmlspecialcharacter()converts special characters to HTML entities. This means htmlentities( ) will check for non English language characters, such as French accents, the German umlaut, etc.

$_SERVER and $_ENV arrays contain different information. The information depends on the server and operating system being used. Most of the information can be seen of an array for a particular server and operating system. The syntax is as follows:

foreach($_SERVER as $key =>$value)

{ echo “Key=$key, Value=$value\n”; }

Super global arrays are the built in arrays that can be used anywhere. They are also called as auto-global as they can be used inside a function as well. The arrays with the longs names such as $HTTP_SERVER_VARS, must be made global before they can be used in an array. This $HTTP_SERVER_VARS check your php.ini setting for long arrays.