Summary of commonly used functions in PHP strings (with examples)

This article brings you a summary of commonly used functions in PHP strings (with examples). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Commonly used functions in PHP:

##str_pad()Pall the string to the specified length$str = "Hello World "; echo str_pad($str,20,".");##str_repeat()str_split()strrev()wordwrap()str_shuffle()parse_str()##number_format()Format numbers by thousands grouping"echo number_format("1000000" ); echo number_format("1000000",2); echo number_format("1000000",2,"","",""."");"Convert string to lowercase##strtoupper()String Convert to uppercaseecho strtoupper("Hello WORLD!");ucfirst()Capitalize the first letter of the stringecho ucfirst("hello world");ucwords()Convert the first character of each word in the string to uppercaseecho ucwords( "hello world");htmlentities()Convert characters to HTML entities$str = ""John & 'Adams'" "; echo htmlentities($str, ENT_COMPAT); 标签##strcasecmp( )Compare two strings without case sensitivityecho strcasecmp("Hello world!","HELLO WORLD!");strcmp ()Compare two strings case-sensitivelystrncmp()Compare the first n characters of the string, Case sensitive##strncasecmp()##strnatcmp()Natural order method compares string length, case sensitiveint strnatcmp (string $str1, string $str2)Natural order method compares string length, case-insensitiveSplit the string into small chunksCut the stringUse one string as a symbol to split another string##implode()Same as join, concatenate the array values ​​into a string using predetermined charactersstring implode ( string $glue , array $pieces ) substr()Intercept string string substr ( string $string , int $start [, int $length ] )mix str_replace(mix $search ,,mix $replace,mix $subject[,int &$num])mix str_ireplace ( mix $search , mix $replace , mix $subject [, int &$count ] ) ##substr_count() Count a string , the number of occurrences in another stringint substr_count ( string $haystack , string $needle [, int $offset = 0 [, int $length ]] )substr_replace()Replace a certain string in the string with another stringmixed substr_replace ( mixed $string , string $replacement , int $start [, int $length ] )similar_text()Returns the number of identical characters in the two stringsint similar_text(str $str1,str $str2)strchr()Returns a string from the beginning to the end of another stringstring strstr (string $str, string $needle, bool $before_needle )strrchr()Returns a string starting from the last occurrence of a string in another string to the endstring strrchr (string $haystack, mixed $needle)stristr()Returns a string from the beginning to the end of another string , not case sensitivestring stristr ( string $haystack , mixed $needle [, bool $before_needle = false ] )strtr()Convert some characters in the stringstring strtr (string $str, string $from, string $to)strpos()Find the position where a certain character first appears in the stringint strpos ( string $haystack , mixed $needle [, int $offset = 0 ] )stripos ()Find the first occurrence of a character in a string, case-insensitiveint stripos ( string $haystack , string $needle [, int $offset ] )strrpos()Find the last occurrence of a character in a stringint strrpos ( string $haystack , string $needle [, int $offset = 0 ] )strripos()Find the last occurrence of a character in a string, case-insensitiveint strripos ( string $haystack , string $needle [, int $offset ] )strspn()Returns the length of the first substring in the string that matches the maskint strspn ( string $str1 , string $str2 [, int $start [, int $length ]] )##iconv_substrIntercept part of the stringiconv_get_encodingGet iconv extended internal configuration variablesmb_substr_countCount the number of occurrences of a stringmb_check_encodingCheck whether the string is valid in the specified encodingmb_strrposFind the last occurrence of a string in a stringmb_splitSplit using regular expressions Multi-byte string##parse_urlNote: mb_* and iconv_* can handle multi-byte characters, such as Chinese.

Function name	Description	Instance
trim()	Remove spaces or other predefined characters at both ends of the string	"$str = "\r\nHello World!\r\n"; echo trim($str);
#rtrim()	Remove spaces or other predefined characters on the right side of the string	"$str = "Hello World!\n\n"; echo rtrim ($str);"
chop()	alias for rtrim()	Same as above
ltrim()	Remove spaces or other predefined characters on the left side of the string	"$str = "\r\nHello World!"; echo ltrim($str);"
dirname()	Return to the directory part of the path (we put it in the string function)	echo dirname("c: /testweb/home.php");
Reuse the specified string	echo str_repeat( ".",13);
Split the string into an array	print_r(str_split("Hello")) ;
Reverse the string	echo strrev("Hello World!");
Wrap the string according to the specified length	"$str = ""An example on a long word is: Supercalifragulistic""; echo wordwrap( $str,15);"
Randomly shuffle all the characters in the string	echo str_shuffle("Hello World" );
Parse the string into a variable	"parse_str("id=23&name=John Adams",$myArray) ; print_r($myArray);"
		##strtolower()
echo strtolower("Hello WORLD!");
	##htmlspecialchars()	Convert predefined characters to html encoding
	nl2br()	\nEscaped to	echo nl2br("One line.\nAnother line.");
strip_tags()	剥去 HTML、XML 以及 PHP 的标签	echo strip_tags("Hello world!");
addcslashes()	Add a backslash before the specified character to escape the characters in the string	$str = "" Hello, my name is John Adams." echo $str; echo addcslashes($str,'m');"
stripcslashes()	Deleted by addcslashes( )Added backslash	echo stripcslashes("Hello, \my na\me is Kai Ji\m.");
addslashes()	Add backslashes before specifying predefined characters	$str = "Who's John Adams?";echo addslashes($str);
stripslashes()	Remove escape characters added by addslashes()	echo stripslashes("Who\'s John Adams?");
quotemeta( )	Add a backslash before some predefined characters in the string	$str = "Hello world. (can you hear me?)"; echo quotemeta($str) ;
chr()	Returns characters from the specified ASCII value	echo chr(052);
ord()	Returns the ASCII value of the first character of the string	echo ord("hello");
Compares the first n characters of the string, not case sensitive	int strncasecmp (string $str1, string $str2, int $len)
		##strnatcasecmp()
int strnatcasecmp ( string $str1 , string $str2 )		chunk_split()
str chunk_split(str $ body[,int $len[,str $end]])		strtok()
str strtok(str $ str,str $token)		explode()
array explode(str $sep ,str $str[,int $limit])
	##str_replace()	String replacement operation, case sensitive
	str_ireplace()	String replacement operation, case-insensitive
strcspn()	Returns the length of the string that does not match the mask	int strcspn (string $str1, string $str2 [, int $start [, int $length ]] )
str_word_count()	Count the number of words contained in a string	mix str_word_count(str $str,[])
strlen()	Statistics string length	int strlen(str $str)
count_chars()	Counts the number of occurrences of all letters in the string (0..255)	mixed count_chars ( string $string [, int $mode ] )
md5()	String md5 encoding	$str = "Hello"; echo md5($str)
iconv
mb_substr	Get the part of the string	string mb_substr (string $str, int $ start [, int $length = NULL [, string $encoding = mb_internal_encoding() ]] )
mb_http_output	Set/get HTTP output character encoding	mixed mb_http_output ([ string $encoding = mb_http_output() ] )
mb_strlen	Get the length of the string	mixed mb_strlen ( string $ str [, string $encoding = mb_internal_encoding() ] )
iconv	The string is converted according to the required character encoding	string iconv ( string $in_charset , string $out_charset , string $str )
Interpret the URL into an array

Chinese mainly uses two encoding formats: GBK and utf-8.

GBK and utf-8 are two different encoding committees’ standards for encoding Chinese characters.

They stipulate that GBK is double-byte, that is, one Chinese character occupies 2Bytes.

utf-8 is three bytes, and one Chinese character occupies three bytes of storage space.

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