PHP Reference Manual

1	Array function
2	Calendar function	The calendar extension contains functions that simplify conversions between different calendar formats.
3	Date/time function	The Date/time function is used to get the date and time and format it from the server that the PHP script is running on.
4	Directory functions	The directory function is used to obtain information about the directory and its contents.
5	error/logging function	The Error/logging function is used to process and record errors.
6	Filesystem function	The Filesystem function is used to access and manipulate the file system.
7	Filter function	PHP filters are used to validate and filter data from non-secure sources, such as user input.
8	FTP functions	The FTP function provides client access to the file server through File Transfer Protocol (FTP).
9	HTTP functions	The HTTP function is used to manipulate information sent by the WEB server to the browser.
10	Libxml function	Libxml functions and constants are used with SimpleXML, XSLT, and DOM functions.
11	Mail function	The Mail () function is used to send e-mail messages directly from the script.
12	Math function	The Math function can handle values in the range of integers and float.
13	Miscellaneous functions	We generalize functions that are not part of other categories to miscellaneous function categories.
14	mysqli function	The MYSQLI function is used to access the MySQL database server.
15	SimpleXML function	The SimpleXML extension provides a simple way to get the name and text of an XML element.
16	String function
17	XML Parser functions	The XML Parser function allows you to create an XML parser and define a handle for an XML event.
18	Zip File function	The zip file function allows you to read compressed files.

PHP Reference Manual