php--most commonly used--must-have function summary! PHP Learner Collection Required!

First, PHP system functions

Function	Function	Usage
Var_dump ()	Print variable structure information, including type and value. Array will recursively expand values	Var_dump ( $arg1...);
Echo (): A grammatical structure	Output one or more strings, without (), enclosed in single or double quotes. Variable direct OUTPUT,	echo $arg 1, $arg 2 ...;
Isset ()	Returns ture if the variable is set and the value is not NULL, and vice versa	Isset ($args)
Empty ()	Detects if the variable is empty	Empty ($args)
Exit ()	Output a message and exit the current version	Exit (' exit successful ')
Die ()	Output a message and stop code execution down	Die (' Code stopped ')
Iconv ()	Character set converted by specified encoding	Iconv (Incharset,outcharset, $STR)
Uniqid ()	Gets a unique ID (no parameter) or gets a unique ID with a prefix based on the current time microseconds (see parameters).	Uniqid ([prefix name],[true])
GetType ()	Get data type	GetType ($args)
Settype ()	Set the variable $arg to a data type	Settype ($args, "[int][string] ...")
Serialize ()	Serialize $arg, i.e. convert to text to save or transfer without losing its type and structure	Serialize (mixed $arg)
Unserialize ()	Deserializes the $STR to return the type and format information before serialization	Unserialize ($STR)
GETCWD ()	Gets the directory where the script is currently running	GETCWD ()
BaseName ()	Returns the Chinese part of the path	BaseName ($url)
Preg_match ()	Use $string to match the regular expression, match the result with $res return match 1 or mismatch 0	Preg_match ($string, regular expression, $res)

Binary conversion function

Function	Function	Usage
Decbin ()	Decimal---binary	Decbin ($num)
DECOCT ()	Decimal-to-octal	Decoct ($num)
Dechex ()	decimal--Hexadecimal	Dechex ($num)
Bindec ()	Binary---decimal	Bindec ($num)
Octdec ()	Octal to Decimal	Octdec ($num)
Hexdec ()	hexadecimal--and decimal	Hexdec ($num)
Base_convert ()	Arbitrary binary conversions	Base_convert (value of the conversion, The value of the binary, to be converted into the system)

English for each system:

Binary: Binary decimal: Decimal

Octal: octect 16 binary: Hexadecimal

Three, constant function

Function	Function	Usage
Define ()	Defines a constant, and the third parameter chooses whether to be case sensitive.	Define (constant name, constant value, "true")
Defined ()	Determine if a constant exists	Define (constant name)
Get_defined_constants ()	Get pre-defined constants	Get_defined_constant ()

Iv. Function of Judgment

Function	Function	Usage
Is_bool ()	Determines whether a Boolean type	Is_bool ()
Is_int ()	Determine if it is an orthopedic	Is_int ()
Is_string ()	Determines whether a string	Is_string ()
Is_float ()	Determines whether a floating-point type	Is_float ()
Is_numeric ()	Determines whether a numeric or numeric string	Is_numeric ()
Is_null ()	Determines whether the empty	Is_null ()
Is_array ()	Determines whether an array	Is_array ()
Is_dir ()	Determine if the path is	Id_dir ()

Five, String function

Function	Function	Usage
Strstr () is an alias for STRCHR ()	Returns the string from the beginning of the $str needle first occurrence of the string to the end. and case-sensitive, do not want to be case-sensitive:stristr ()	strstr ($str , $needle )
Strpos ()	Gets the position (subscript) of the first occurrence of $needle in $str, without returning false	Strpos ($str, $needle)
Strrpos ()	Gets the position (subscript) of the last occurrence of $needle in $str, without returning false	Strrpos ($str, $needle)
SUBSTR ()	Intercept string $str from $start position to $length string	substr ($str, $start, $length)
Implode ()	To concatenate arrays into strings.	Implode (', ', $arr)
Explode ()	To divide the string into groups	Explode (', ', $str)
Str_split ()	Divide the string $str into an array of 5 per unit length	Str_split ($STR, 5)
Str_replace ()	Replace a in string $str with B	Str_replace (A, B, $str)
Strtolower ()	String converted to lowercase	Strtolower ($STR)
Strtoupper ()	Convert string to uppercase	Strtoupper ($STR)
Ucfirst ()	Converts a string $str the first character to uppercase	Ucfirst ($STR)
Unwords ()	Converts each word in a string to an uppercase letter $str	Unwords ($STR)
Trim ()	Remove whitespace characters and other characters at both ends of a string	Trim ($STR)
RTrim ()	Remove whitespace characters and other characters to the right of a string	RTrim ($STR)
Strlen ()	Get string length	Strlen ($STR)
Substr_count ()	Count the number of occurrences of a string $ A in the $STR string	Substr_count ($STR, "$a")
Str_repeat ()	Repeat output $str, number of $num	Str_repeat ($str, $num)
Strpad ()	Use 0 padding on the left side of the $str to make the length $length	Strpad ($str, $length, "0", Str_pad_left)
Strrev ()	Flip String Order	Strrev ($STR)
RAND ()	Take a random integer between m-n	Rand (M,N)
Mt_rand ()	Take a random integer between M-n to get faster than Mt_rand ()	Mt_rand (M,n)
POW ()	Take M's n-th square	Pow (m,n)
Number_format ()	Format a number in thousands separator mode	Number_format ($n)

six, array functions

Function	Role	Usage
Unset ()	Destroys the specified variable	Unset ($arr)/unset ($arr [n])
Array_values ()	Gets all the values in the array and re-establishes the numeric subscript	Array_values ($arr)
Array_keys ()	Gets all the key values in the array	Array_keys ($arr)
Is_array ()	Determines whether an array	Is_array ($arr)
In_array ()	Determines whether an array $arr contains an element $str	In_array ($str, $arr)
Count ()	Statistic array length/statistic multidimensional array length	Count ($arr)/count ($arr, 1)
Range ()	Create an array of 1-9	Rang (1,9), range (A-Z)
Array_merge ()	Concatenate multiple arrays into an array	Array_merge ($arr, $brr ...)
Array_rand ()	Randomly extracts n cells in the array, returns the key value, becomes the new array	Array_rand ($arr, N)
Shuffle ()	Scrambled Array Order	Shuffle ($arr)
each ()	Returns the key/value pair of the current element in the array and automatically moves the array pointer forward one step	each ($arr)
List (): Language structure	Assign the values in the array to some variables	List ($a, $b, $c) = $arr
Array_unshift ()	Insert one or more cells at the beginning of an array	Array_unshift ($arr, $v 1, $v 2 ...)
Array_push ()	Inserts one or more cells at the end of the array	Array_push ($arr, $v 1, $v 2 ...)
Array_pop ()	The last element of the array is removed and returned	Array_pop ($arr)
Array_key_exist ()	Determine if the key $k exists in the array	Array_key_exist ($k, $arr)
Array_search ()	Searches the array for the given value $v, and returns the corresponding key name if successful	Array_search ($v, $arr)
Array_flip ()	Swap the keys and values of an array	Array_flip ($arr)
Array_count_values ()	Count the number of occurrences of all values in the array	Array_count_values ($arr)
Array_unique ()	Move duplicate values in an array	Array_unique ($arr)
Sort ()	Sort the array in ascending order of the size of the values	Sort ($arr)
Asort ()	Arranges the array in ascending order of value and keeps the index relationship	Asort ($arr)
Rsort ()	Arranges the array in descending order of the size of the values, rearranging the indexes	Rsort ($arr)
Arsort	Sorts the array in descending order of the size of the values, keeping the index	Arsort ($arr)
Natsort ()	Natural sorting (in line with People's Daily habits)	Natsort ($arr)
Ksort ()	Arranges arrays in descending order of key size, preserving the association of key names to data	Ksort ($arr)
Krsort ()	Arranges arrays in descending order of key size, preserving the association of key names to data	Krsort ($arr)
Array_sum ()	Sum all the values in an array	Array_sum ($arr)
Key ()	Gets the position of the traversal pointer in the array (key)	Key ($arr)
Current ()	Get the value of the position where the pointer is	Current ($arr)
Next ()	Moves the pointer back one position in the array	Next ($arr)
Prev ()	Move the pointer in the array forward one position	Prev ($arr)
Reset ()	Resets the position of the pointer in the array (pointing to the first position)	Reset ($arr)
End ()	Move the pointer in the array to the last position	End ($arr)

Seven, Time function

Function	Role	Usage
Time ()	Gets the current time stamp	Time ()
Mktime ()	Gets the timestamp for the specified time	Mktime (hours, minutes, seconds, months, days, years)
Date ()	$tmp time to specified format output	Date (' y-m-d h:i:s ', $tmp)
Strtotime ()	Resolves a datetime description of any English text to a Unix timestamp	Strtotime ("Now")

Viii. database functions

Function	Function	Role
Mysql_connect ()	Link MySQL Database	Mysql_connect ($host, $user, $pwd)
mysql_query ()	Send a MySQL statement	mysql_query (SQL statement)
MYSQL_FETCH_ASSOC ()	Takes a row of data in the result set to form an associative array and returns, and continues to move the internal data pointer	MYSQL_FETCH_ASSOC ($result)
Mysql_fetch_array ()	Takes a row of data in the result set to form an array and returns, and continues to move the internal data pointer	Mysql_fetch_array ($result, parameters)
Mysql_fetch_row ()	Takes a row of data in the result set to form an indexed array and returns, and continues to move the internal data pointer	Mysql_fetch_row ($result)
mysql_select_db ()	Select Database	mysql_select_db (database name)
Mysql_num_rows ()	Gets the number of query result records	Mysql_num_rows (query result)

Nine, file operation function

fopen ()	Open file or URL	fopen ("filename", "mode")
Fwrite ()	Writing content in a file	Fwrite ("filename", "content")
Fclose ()	Close a file or URL	fclose ("filename")
File_put_contents ()	Write content in one step	File_put_contents ("filename", "content")
File_get_contents ()	Read content in one step	file_get_contents ("filename", "content")
Fread ()	Reads the contents of a specified length file	Fread ("filename", number of bytes)
FileSize ()	Get file content Length (in bytes)	FileSize ("filename")
Fgets ()	Read a row	Fgets ($handle, length)
File ()	To read an entire file into an array	File ("filename")
Copy ()	Copy the file, the new file is named "NewFile"	Copy ("filename", "NewFile")
Unlink ()	deleting files	Unlink ($filename)
Filectime ()	Get File creation time	Filectime ($filename)
Fileatime ()	Get file last access time	Fileatime ($filename)
Filemtime ()	Get File modification Time	Filemtime ($filename)
Feof ()	Determines whether the pointer reaches the end of the file	Feof ($filename)
Json_encode ()	Compiling data into JSON data	Json_encode ($a)
Json_decode ()	Encode JSON data into PHP data variables When the argument is true, returns an array	Json_decode ($j, [false]/true)

10. Directory Operation function

Function	Function	Usage
mkdir ()	Create a directory with 0777 recursively created	mkdir ("/path/to/my/dir", 0777);
RmDir ()	Delete Directory	RmDir ($DIR)
Opendir ()	Open Directory Handle	Opendir ($dir)
Readdir ()	Read Directory	Readdir ($dir)
Closedir ()	Close Directory	Closedir ($dir)
Rewinddir ()	Resetting Directory Resources	Rewinddir ($dir)
File_exists ()	Determine if a file/directory exists	File_exists ($filename/$dir)
Rename ()	Renaming files/Directories	Rename ($filename/$dir, $newname)
DirName ()	DirName ($path)	Returns the directory portion of the path
BaseName ()	Returns the file name portion of the path	BaseName ($path)
PathInfo ()	Get path information	PathInfo ($path, [options])

11. Class Functions

Function	Function	Role
Class_exists ()	Determine if a class exists	Class_exists ($classname)
Interface_exists ()	Determine if an interface exists	Interface_exists ($name)
Method_exists ()	Determine if the method exists	Method_exists ($name)
Property_exists ()	Determine if a property exists	Property ($name)
Get_class ()	Get class Name	Get_class ()
Get_parent_class ()	Get Parent class Name	Get_parent_class ()
Get_class_methods ()	Getting methods in a class	Get_class_methods ()
Get_class_vars ()	Returns an array that consists of the default properties of the class	Get_class_vars ()
Get_declared_class ()	Gets the name of the class that is defined	Get_declared_class ()
__tostring ()	Called when the object is treated as a string	__tostring ()
__construct ()	Automatically called when the new object	__construct ()
__destruct ()	Automatically called when objects are destroyed	__destruct ()
__clone ()	Automatically called when cloning an object	__clone ()
__invoke ()	Automatically called when an object is called as a function	__invoke ()
__set ()	Automatically called when a value is assigned to an inaccessible member property	__set ()
__get ()	Automatically called when reading the value of a non-readable member property	__get ()
__isset ()	Automatically called when using Isset () or empty () for an inaccessible member property	__isset ()
__unset ()	Auto-tune when using unset () for inaccessible member properties	__unset ()
Class_alias ()	Create an alias for a class	Class_alias (original class, category name)
Get_object_vars ()	Returns an associative array containing the defined properties and values that are available for object	Get_object_vars ()
Is_a ()	Returns TRUE if the object belongs to the class or if the class is the parent class of this object	Is_a ($obj, $classname)
Is_subclass_of ()	Returns TRUE if the object owning class is a subclass of class class_name, otherwise FALSE is returned.	Is_subclass_of ($obj, $classname)

php--most commonly used--must-have function summary! PHP Learner Collection Required!