The limitations of cookies :-
1) the cokkie specification says that
I) no cookie can exceed 4KB in size,
II) only 20 cookies are allowed per domain ,
III) and a total of 300 cookies can be stored on the client side
2) There is no control over when the browsers actually expire cookies.
Type juggling :-
1) The conversion of a value from one type to another is called casting.
2) This kind of implicit casting is called type juggling in PHP.
Regular expressions:-
1) Definition :- A regular expression is a string that represents a pattern .The regular expression functions compare that pattern to another string and see if any of the string matches the pattern .Some functions tell you whether there was a match, while others make changes to the string.
2) PHP provides support for two different types of regular expressions :
1) POSIX and
2) Perl- compatible
3) POSIX regular expressions are less powerful and sometimes slower , than the Perl - compatible functions ,but can be easier to read.
4)There are three uses for regular expressions:
1) matching ,which can also be used to extract information from a string ;
2) substituting new text for matching text; and
3) spilitting a string into an array of smaller chunks.
5) PHP has functions for all three behaviours for both Perl and POSIX regular expressions .For instance ,erg() does a POSIX match ,while preg_match() does a Perl match .
6) Fortunately ,there are a number of similarities between basic POIX and Perl regular expressions, so we'll cover those before dealing into the details of each library.
Serialzation:-
1) Serializing an object means converting it to bytestream representation that can be stored in a file. This is useful for persistent data , for example , PHP sessions automatically save and restore object.
2) Serialization in PHP is mostly automatic - it requires little extra work from you.
