CXLII. String 字符串处理函数

简介

本类函数用来对字符串进行各种操作。对字符串的一些其它专门操作,可以参考手册的正则表达式部分和 URL 操作部分。

如果想要了解字符串的相关内容,特别是有关单引号,双引号等的处理部分,可以参考手册中类型部分中的字符串条目。

需求

要编译本扩展模块不需要外部库文件。

安装

本函数库作为 PHP 内核的一部分,不用安装就能使用。

预定义常量

以下常量由本扩展模块定义,因此只有在本扩展模块被编译到 PHP 中,或者在运行时被动态加载后才有效。

CRYPT_SALT_LENGTH integer

CRYPT_STD_DES integer

CRYPT_EXT_DES integer

CRYPT_MD5 integer

CRYPT_BLOWFISH integer

HTML_SPECIALCHARS (integer)

HTML_ENTITIES (integer)

ENT_COMPAT (integer)

ENT_QUOTES (integer)

ENT_NOQUOTES (integer)

CHAR_MAX (integer)

LC_CTYPE (integer)

LC_NUMERIC (integer)

LC_TIME (integer)

LC_COLLATE (integer)

LC_MONETARY (integer)

LC_ALL (integer)

LC_MESSAGES (integer)

STR_PAD_LEFT (integer)

STR_PAD_RIGHT (integer)

STR_PAD_BOTH (integer)

参见

如果想更深入的了解有关字符串高级操作的相关内容,请参阅手册的 POSIX 扩展正则表达式函数Perl 兼容正则表达式函数部分。

目录
addcslashes -- 像 C 那样使用反斜线转义字符串中的字符
addslashes -- 使用反斜线引用字符串
bin2hex --  将二进制数据转换成十六进制表示
chop -- rtrim() 的别名函数
chr -- 返回指定的字符
chunk_split -- 将字符串分割成小块
convert_cyr_string --  将字符由一种 Cyrillic 字符转换成另一种
convert_uudecode --  Decode a uuencoded string
convert_uuencode --  Uuencode a string
count_chars --  返回字符串所用字符的信息
crc32 -- 计算一个字符串的 crc32 多项式
crypt -- One-way string encryption (hashing)
echo -- Output one or more strings
explode -- 使用一个字符串分割另一个字符串
fprintf -- Write a formatted string to a stream
get_html_translation_table --  Returns the translation table used by htmlspecialchars() and htmlentities()
hebrev --  Convert logical Hebrew text to visual text
hebrevc --  Convert logical Hebrew text to visual text with newline conversion
html_entity_decode --  Convert all HTML entities to their applicable characters
htmlentities --  Convert all applicable characters to HTML entities
htmlspecialchars_decode --  Convert special HTML entities back to characters
htmlspecialchars --  Convert special characters to HTML entities
implode -- Join array elements with a string
join -- 别名 implode()
levenshtein --  Calculate Levenshtein distance between two strings
localeconv -- Get numeric formatting information
ltrim --  Strip whitespace (or other characters) from the beginning of a string
md5_file -- Calculates the md5 hash of a given file
md5 -- Calculate the md5 hash of a string
metaphone -- Calculate the metaphone key of a string
money_format -- Formats a number as a currency string
nl_langinfo --  Query language and locale information
nl2br --  Inserts HTML line breaks before all newlines in a string
number_format -- Format a number with grouped thousands
ord -- Return ASCII value of character
parse_str -- Parses the string into variables
print -- Output a string
printf -- Output a formatted string
quoted_printable_decode --  Convert a quoted-printable string to an 8 bit string
quotemeta -- Quote meta characters
rtrim --  Strip whitespace (or other characters) from the end of a string
setlocale -- Set locale information
sha1_file -- Calculate the sha1 hash of a file
sha1 -- Calculate the sha1 hash of a string
similar_text --  Calculate the similarity between two strings
soundex -- Calculate the soundex key of a string
sprintf -- Return a formatted string
sscanf --  Parses input from a string according to a format
str_ireplace --  Case-insensitive version of str_replace().
str_pad --  Pad a string to a certain length with another string
str_repeat -- Repeat a string
str_replace --  Replace all occurrences of the search string with the replacement string
str_rot13 -- Perform the rot13 transform on a string
str_shuffle -- Randomly shuffles a string
str_split --  Convert a string to an array
str_word_count --  Return information about words used in a string
strcasecmp --  Binary safe case-insensitive string comparison
strchr -- 别名 strstr()
strcmp -- Binary safe string comparison
strcoll -- Locale based string comparison
strcspn --  Find length of initial segment not matching mask
strip_tags -- Strip HTML and PHP tags from a string
stripcslashes --  Un-quote string quoted with addcslashes()
stripos --  Find position of first occurrence of a case-insensitive string
stripslashes --  Un-quote string quoted with addslashes()
stristr --  Case-insensitive strstr()
strlen -- Get string length
strnatcasecmp --  Case insensitive string comparisons using a "natural order" algorithm
strnatcmp --  String comparisons using a "natural order" algorithm
strncasecmp --  Binary safe case-insensitive string comparison of the first n characters
strncmp --  Binary safe string comparison of the first n characters
strpbrk --  Search a string for any of a set of characters
strpos --  Find position of first occurrence of a string
strrchr --  Find the last occurrence of a character in a string
strrev -- Reverse a string
strripos --  Find position of last occurrence of a case-insensitive string in a string
strrpos --  Find position of last occurrence of a char in a string
strspn --  Find length of initial segment matching mask
strstr -- Find first occurrence of a string
strtok -- Tokenize string
strtolower -- Make a string lowercase
strtoupper -- Make a string uppercase
strtr -- Translate certain characters
substr_compare --  Binary safe optionally case insensitive comparison of 2 strings from an offset, up to length characters
substr_count -- Count the number of substring occurrences
substr_replace -- Replace text within a portion of a string
substr -- Return part of a string
trim -- Strip whitespace (or other characters) from the beginning and end of a string
ucfirst -- Make a string's first character uppercase
ucwords --  Uppercase the first character of each word in a string
vfprintf -- Write a formatted string to a stream
vprintf -- Output a formatted string
vsprintf -- Return a formatted string
wordwrap --  Wraps a string to a given number of characters using a string break character

add a note add a note User Contributed Notes
beggining pro
03-Aug-2006 02:00
Well for you egold users out ther I wrote this to just return the balance ONLY
If anyone knows a better way to write this lemme know as im a novice

   function _GetBalance($from, $frompass) {
   $defined_vars = get_defined_vars();

   $_url = 'https://www.e-gold.com/acct/balance.asp';

       $_url_p = "AccountID=" . $from . "&PassPhrase=" . $frompass ."";
           $ch = curl_init();

   curl_setopt($ch, CURLOPT_POST,1);
   curl_setopt($ch, CURLOPT_POSTFIELDS,$_url_p);
   curl_setopt($ch, CURLOPT_URL,$_url);
   curl_setopt($ch, CURLOPT_SSL_VERIFYHOST,  2);
   curl_setopt($ch, CURLOPT_USERAGENT, $defined_vars['HTTP_USER_AGENT']);
   curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
   $content = curl_exec ($ch);

   curl_close ($ch);
$content=strtolower($content);
$content=strstr($content,"</select></font></th></form></tr>");
$content=strip_tags($content);
$content=strrev($content);
$content=strstr($content,"eseht :eton");
$content=str_replace("eseht :eton","",$content);
$content=ltrim($content);
$content=rtrim($content);
$content=substr($content,0,11);
$content=strrev($content);
$content=ltrim($content);

   return $content;

   }
admin at rotarymulundeast dot org
30-Jul-2006 06:16
Here's an easier way to find nth...

function nth($numbex){
  if ($numbex%10 == 1 && $numbex%100 != 11) $sth='st';
  elseif ($numbex%10 == 2 && $numbex%100 != 12) $sth='nd';
  elseif ($numbex%10 == 3 && $numbex%100 != 13) $sth='rd';
  else $sth = 'th';
  return $sth;
}

there is is no need to check if the user has entered a non-integer as we may be using this function for expressing variables as well eg. ith value of x , nth root of z ,etc...
heavyraptor
27-Jul-2006 11:17
I think that
administrador(ensaimada)sphoera(punt)com's function is
too complicated. It's easier with regular expressions.
So I made this function, it isn't really the same,
it's even better because it returns an array with all the
matches found
If there are no matches, false is returned.

<?php
// bool/array str_between( string str, string
start_str, string end_str )
function
str_between($str,$start,$end) {
  if (
preg_match_all('/' . preg_quote($start) . '(.*?)' . preg_quote($end) . '/',$str,$matches)) {
   return
$matches[1];
  }
 
// no matches
 
return false;
}
?>

Enjoy
da (dot) blayde (a t) gmail (dot) com
20-Jul-2006 01:52
Sometimes when converting integers to strings, it looks better to have the number spelled out. I wrote this function that converts integers from -999 to 999 into spelled out strings:

function int2str($int=0){
 $doOnes=true;
 $neg=$int<0?true:false;
 $int=abs(round($int));
 $str='';
 switch(strlen($int)){
  case 1:$int='0'.$int;
  case 2:$int='0'.$int;
  case 3:$int.='';break;
  default:return $int;
 }
 switch($int{0}){
  case 1:$str.='one-hundred-';break;
  case 2:$str.='two-hundred-';break;
  case 3:$str.='three-hundred-';break;
  case 4:$str.='four-hundred-';break;
  case 5:$str.='five-hundred-';break;
  case 6:$str.='six-hundred-';break;
  case 7:$str.='seven-hundred-';break;
  case 8:$str.='eight-hundred-';break;
  case 9:$str.='nine-hundred-';break;
 }
 switch($int{1}){
  case 1:
   switch($int{2}){
   case 0:$str.='ten-';break;
   case 1:$str.='eleven-';break;
   case 2:$str.='twelve-';break;
   case 3:$str.='thirteen-';break;
   case 4:$str.='fourteen-';break;
   case 5:$str.='fifteen-';break;
   case 6:$str.='sixteen-';break;
   case 7:$str.='seventeen-';break;
   case 8:$str.='eighteen-';break;
   case 9:$str.='nineteen-';break;
   }
   $doOnes=false;
  break;
  case 2:$str.='twenty-';break;
  case 3:$str.='thirty-';break;
  case 4:$str.='forty-';break;
  case 5:$str.='fifty-';break;
  case 6:$str.='sixty-';break;
  case 7:$str.='seventy-';break;
  case 8:$str.='eighty-';break;
  case 9:$str.='ninety-';break;
 }
 if($doOnes){
  switch($int{2}){
   case 1:$str.='one-';break;
   case 2:$str.='two-';break;
   case 3:$str.='three-';break;
   case 4:$str.='four-';break;
   case 5:$str.='five-';break;
   case 6:$str.='six-';break;
   case 7:$str.='seven-';break;
   case 8:$str.='eight-';break;
   case 9:$str.='nine-';break;
 }}
 $str=substr($str,0,-1);
 if($neg){
  $str='negative '.$str;
 }
 if($int=='000'){
  $str='zero';
 }
 return $str;
}

Hope this helps someone,
-Blayde
mickycole at hotmail dot com
19-Jul-2006 03:01
In responce to James Baker's sencence case function.
Great function however i would make one slight variation being that it doesn't take into account the fact that a capital is required after a new paragraph so i modified it to check for /r and /n as follows:
<?PHP
/*/ Author : James Baker /*/
function sentenceCase($s){
  
$str = strtolower($s);
  
$cap = true;
 
   for(
$x = 0; $x < strlen($str); $x++){
      
$letter = substr($str, $x, 1);
       if(
$letter == "." || $letter == "!" || $letter == "?" || $letter == "\n" || $letter == "\r"){
          
$cap = true;
       }elseif(
$letter != " " && $cap == true){
          
$letter = strtoupper($letter);
          
$cap = false;
       }
    
      
$ret .= $letter;
   }
 
   return
$ret;
}
?>
administrador(ensaimada)sphoera(punt)com
02-Mar-2006 10:10
I've prepared this simple function to obtain a string delimited between tags (not only XML tags!). Anybody needs something like this?.

<?php

function get_string_between($string, $start, $end){
  
$string = " ".$string;
    
$ini = strpos($string,$start);
     if (
$ini == 0) return "";
    
$ini += strlen($start);   
    
$len = strpos($string,$end,$ini) - $ini;
     return
substr($string,$ini,$len);
}

$string = "this [custom] function is useless!!";
echo
get_string_between($string,"[","]");
// must return "custom";
?>
more functions at http://www.sphoera.com
SteveRusin
25-Feb-2006 03:00
The functions below:

function beginsWith( $str, $sub )
function endsWith( $str, $sub )

Are correct, but flawed.  You'd need to use the === operator instead:

function beginsWith( $str, $sub ) {
   return ( substr( $str, 0, strlen( $sub ) ) === $sub );
}
function endsWith( $str, $sub ) {
   return ( substr( $str, strlen( $str ) - strlen( $sub ) ) === $sub );
}

Otherwise, endsWith would return "foobar.0" ends with ".0" as well as "0" or "00" or any amount of zeros because numerically .0 does equal 0.
navarr at gmail dot com
21-Dec-2005 10:24
stripos for PHP4.x

<?php
 
function stripos($haystack,$needle) {
   return
strpos(strtoupper($haystack),strtoupper($needle));
  }
?>
dkflbk at nm dot ru
12-Dec-2005 12:58
I needed str2bin() function for one of my project, so if some one else is want to use it, have fun :)

<?php
/**
 *    Returns an ASCII string containing
 *    the binary representation of the input data .
**/
function str2bin($str, $mode=0) {
  
$out = false;
   for(
$a=0; $a < strlen($str); $a++) {
      
$dec = ord(substr($str,$a,1));
      
$bin = '';
       for(
$i=7; $i>=0; $i--) {
           if (
$dec >= pow(2, $i) ) {
              
$bin .= "1";
              
$dec -= pow(2, $i);
           } else {
              
$bin .= "0";
           }
       }
      
/* Default-mode */
      
if ( $mode == 0 ) $out .= $bin;
      
/* Human-mode (easy to read) */
      
if ( $mode == 1 ) $out .= $bin . " ";
      
/* Array-mode (easy to use) */
      
if ( $mode == 2 ) $out[$a] = $bin;
   }
   return
$out;
}
?>
admin at fivestarbuy dot com
22-Oct-2005 12:18
This example lets you parse an unparsed strings variables. Warning: This could cause security leaks if you allow users to pass $variables through this engine. I recommend only using this for your Content Management System.

<?
$mytime
=time();
$mydog="My Dog Ate My PHP!";

# Your Parsing String:
$s1 = 'Hyphen Variable Preserving: $mytime, and $mydog';
echo
"Before: <br><br>$s1<br><br>";

# Remember, wherever you define this, it will not be defined GLOBAL into the function
# which is why we define it here. Defining it global could lead to security issues.
$vardata=get_defined_vars();

# Parse the string
$s1 = StrParse($s1,$vardata);

echo
"After: <br><br>$s1";

function
StrParse($str,$vardata) {
# Takes a string, or piece of data, that contains PHP Variables
 
 # For example, unparsed variables like:  Test using time: $mytime
 # This example shows $mytime, and not the actual variable value.
 # The end result shows the actual variable value of $mytime.

 # This is useful for building a content management system,
 # and directing your variables into your content data,
 # where content is stored in a file or database, unparsed.
 # Of course this could slow down page loads, but it's a good way
 # to parse data from current variables into your loaded new data
 # making it compatible.
 
# Then the variables are replaced with the actual variable..
$getvarkeys=array_keys($vardata);
$ret=$str;
for (
$x=0; $x < count($getvarkeys); $x++) {
  
$myvar=$getvarkeys[$x];
  
#echo "Variable: " . $myvar . " [" . $vardata[$myvar] . "]<br>";
  
$ret=str_replace('$' . $myvar, $vardata[$myvar], $ret);
}
return
$ret;

}

?>
18-Oct-2005 06:27
to: james dot d dot baker at gmail dot com

PHP has a builtin function  for doing what your function does,

http://php.net/ucfirst
http://php.net/ucwords
14-Oct-2005 11:24
Updated; used to test for input as an array, should have been a string, added some validation of the input while I was at it.  Enjoy.

<?php
/*----------        Directory Tree to Array        ----------//
  Takes base directory, returns an associative array
       containing each directory name as an associative key
       and each file as an indexed entry in the appropriate
       directory.
  If no path is provided, it uses the current directory
  If $style == 1, it will return a sorted, non-associative
       array

  By Peter Dolan
  www.peterd.net
  Updated 2005-10-12

  Use it as much as you like for whatever
  For my own entertainment, please let me know if you do
//-----------------------------------------------------------*/
function dirTreeToArray( $path = "./", $style="0" ) {
     if ( !
is_string($path) or !($style==0 or $style==1) ) die("Improper arguments in function dirTreeToArray(string \$path, \$style = {0, 1})");
     else {
      
$path = trim($path);
      
$path = str_replace("\\", "/", $path);
       if(
'/' == $path{strlen($path)-1} || '\'' == $path{strlen($path)-1} ) $path = substr($path, 0, strlen($path)-1);
     }
    
$tree = array();
    
$arrayPointer = & $tree;
   if (
$handle = opendir($path) ) {
       while (
$fileName = readdir($handle) ) {
             if (
$fileName != "." and $fileName != ".." ) {
                      
$newPath = "$path/$fileName";        // Used for testing directory or file property
                
if ( is_dir($newPath) ) {
                  
$dummyPointer = & $arrayPointer;        // Save the current pointer
                    
if ( $style == 0 ) $arrayPointer = & $arrayPointer[$fileName];    // Drop the pointer into a subdirectory
                    
elseif ( $style == 1 ) $arrayPointer = & $arrayPointer[];        // Drop the pointer into a subdirectory
                    
$arrayPointer = dirTreeToArray($newPath, $style);            // Process the new subdirectory
                  
if ( $style == 1 ) sort($arrayPointer);    // Sort it if we're in a non-associative mode
                    
$arrayPointer = & $dummyPointer;        // Bring the pointer back up a level
              
}
                 elseif (
is_file($newPath) ) $arrayPointer[] = $fileName;    // Enter the files
          
}
       }
               return
$tree;
   }
   else die(
"Failed to open directory $path in function dirTreeToArray(string \$path, \$style = {0, 1})");
}
?>
tim_meredith at s4s dot org
14-Oct-2005 04:32
--Convert MSWord Quotes--
Use this before any conversion to HTML entities or characters to clean up a form entry cut and pasted from MSWord.

function fixword($scratch)
{
   $start=chr(226).chr(128);
   $word=array();$fixword=array();
   $word[]=$start.chr(152);$fixword[]="'";
   $word[]=$start.chr(153);$fixword[]="'";
   $word[]=$start.chr(156);$fixword[]="\"";
   $word[]=$start.chr(157);$fixword[]="\"";
   return str_replace($word, $fixword, $scratch);
}
webmaster at cafe-clope dot net
14-Aug-2005 07:40
A comprehensive concatenation function, that works with array and strings

<?php
function str_cat() {
 
$args = func_get_args() ;
  
 
// Asserts that every array given as argument is $dim-size.
  // Keys in arrays are stripped off.
  // If no array is found, $dim stays unset.
 
foreach($args as $key => $arg) {
   if(
is_array($arg)) {
     if(!isset(
$dim))
      
$dim = count($arg) ;
     elseif(
$dim != count($arg))
       return
FALSE ;
    
$args[$key] = array_values($arg) ;
   }
  }
      
 
// Concatenation
 
if(isset($dim)) {
  
$result = array() ;
   for(
$i=0;$i<$dim;$i++) {
    
$result[$i] = '' ;
     foreach(
$args as $arg)
      
$result[$i] .= ( is_array($arg) ? $arg[$i] : $arg ) ;
   }
   return
$result ;
  } else {
   return
implode($args) ;
  }
}
?>

A simple example :

<?php
str_cat
(array(1,2,3), '-', array('foo' => 'foo', 'bar' => 'bar', 'noop' => 'noop')) ;
?>

will return :
Array (
  [0] => 1-foo
  [1] => 2-bar
  [2] => 3-noop
)

More usefull :

<?php
$myget
= $_GET ; // retrieving previous $_GET values
$myget['foo'] = 'b a r' ; // changing one value
$myget = str_cat(array_keys($myget), '=', array_map('rawurlencode', array_values($myget))) ;
$querystring = implode(ini_get('arg_separator.output'), $myget)) ;
?>

will return a valid querystring with some values changed.

Note that <?php str_cat('foo', '&', 'bar') ; ?> will return 'foo&bar', while <?php str_cat(array('foo'), '&', 'bar') ; ?> will return array(0 => foo&bar)
t0russ at gmail dot com
15-Jun-2005 01:38
to kristin at greenaple dot on dot ca:
thanx for sharing.
your function in recursive form proved to be slightly faster and it returns false (as it should) when the character is not found instead of number 0:
<?php
function strnposr($haystack, $needle, $occurance, $pos = 0) {
   return (
$occurance<2)?strpos($haystack, $needle, $pos):strnposr($haystack,$needle,$occurance-1,strpos($haystack, $needle, $pos) + 1);
}
?>
rh at richardhoward dot net
06-Jun-2005 02:41
<?php
/**
Utility class: static methods for cleaning & escaping untrusted (i.e.
user-supplied) strings.

Any string can (usually) be thought of as being in one of these 'modes':

pure = what the user actually typed / what you want to see on the page /
       what is actually stored in the DB
gpc  = incoming GET, POST or COOKIE data
sql  = escaped for passing safely to RDBMS via SQL (also, data from DB
       queries and file reads if you have magic_quotes_runtime on--which
       is rare)
html = safe for html display (htmlentities applied)

Always knowing what mode your string is in--using these methods to
convert between modes--will prevent SQL injection and cross-site scripting.

This class refers to its own namespace (so it can work in PHP 4--there is no
self keyword until PHP 5). Do not change the name of the class w/o changing
all the internal references.

Example usage: a POST value that you want to query with:
$username = Str::gpc2sql($_POST['username']);
*/

//This sets SQL escaping to use slashes; for Sybase(/MSSQL)-style escaping
// ( ' --> '' ), set to true.
define('STR_SYBASE', false);

class
Str {
   function
gpc2sql($gpc, $maxLength = false)
   {
       return
Str::pure2sql(Str::gpc2pure($gpc), $maxLength);
   }
   function
gpc2html($gpc, $maxLength = false)
   {
       return
Str::pure2html(Str::gpc2pure($gpc), $maxLength);
   }
   function
gpc2pure($gpc)
   {
       if (
ini_get('magic_quotes_sybase'))
          
$pure = str_replace("''", "'", $gpc);
       else
$pure = get_magic_quotes_gpc() ? stripslashes($gpc) : $gpc;
       return
$pure;
   }
   function
html2pure($html)
   {
       return
html_entity_decode($html);
   }
   function
html2sql($html, $maxLength = false)
   {
       return
Str::pure2sql(Str::html2pure($html), $maxLength);
   }
   function
pure2html($pure, $maxLength = false)
   {
       return
$maxLength ? htmlentities(substr($pure, 0, $maxLength))
                         :
htmlentities($pure);
   }
   function
pure2sql($pure, $maxLength = false)
   {
       if (
$maxLength) $pure = substr($pure, 0, $maxLength);
       return (
STR_SYBASE)
               ?
str_replace("'", "''", $pure)
               :
addslashes($pure);
   }
   function
sql2html($sql, $maxLength = false)
   {
      
$pure = Str::sql2pure($sql);
       if (
$maxLength) $pure = substr($pure, 0, $maxLength);
       return
Str::pure2html($pure);
   }
   function
sql2pure($sql)
   {
       return (
STR_SYBASE)
               ?
str_replace("''", "'", $sql)
               :
stripslashes($sql);
   }
}
?>
james dot d dot baker at gmail dot com
28-May-2005 01:45
<?php
/*
Written By James Baker, May 27th 2005

sentenceCase($string);
   $string: The string to convert to sentence case.

Converts a string into proper sentence case (First letter of each sentance capital, all the others smaller)

Example Usage:
echo sentenceCase("HELLO WORLD!!! THIS IS A CAPITALISED SENTENCE. this isn't.");

Returns:
Hello world!!! This is a capitalised sentence. This isn't.
*/

function sentenceCase($s){
  
$str = strtolower($s);
  
$cap = true;
  
   for(
$x = 0; $x < strlen($str); $x++){
      
$letter = substr($str, $x, 1);
       if(
$letter == "." || $letter == "!" || $letter == "?"){
          
$cap = true;
       }elseif(
$letter != " " && $cap == true){
          
$letter = strtoupper($letter);
          
$cap = false;
       }
      
      
$ret .= $letter;
   }
  
   return
$ret;
}
?>
php at moechofe dot com
26-Apr-2005 09:34
<?php
 
/*
  * str_match
  *
  * return a string with only cacacteres defined in a expression return false if the expression is not valid
  *
  * @param $str string the string
  * @param $match the expression based on the class definition off a PCRE regular expression.
  *  the '[', ']', '\' and '^' at class start need to be escaped.
  *  like : -a-z0-9_@.
  */
 
function str_match( $str, $match )
  {
  
$return = '';
   if(
eregi( '(.*)', $match, $class ) )
   {
    
$match = '['.$regs[1].']';
     for(
$i=0; $i<strlen($str); $i++ )
     if(
ereg( '['.$class[1].']', $str[$i] ) )
    
$return .= $str{$i};
     return
$return;
   }
   else return
false;
  }

 
/*
  * example
  * accept only alphanum caracteres from the GET/POST parameters 'a'
  */

 
if( ! empty($_REQUEST['a']) )
  
$_REQUEST['a'] = str_match( $_REQUEST['a'], 'a-zA-Z0-9' );
  else
  
$_REQUEST['a'] = 'default';
?>
Pommef
20-Mar-2005 05:15
Example: Give me everything up to the fourth occurance of '/'.

<?php

   $haystack
= "/home/username/www/index.php";
  
$needle = "/";
 
   function
strnpos($haystack, $needle, $occurance, $pos = 0) {
      
      
$res = implode($needle,$haystack);
      
      
$res = array_slice($res, $pos$occurance);
      
       return
explode ($needle,$res);
   }
?>
kristin at greenapple dot on dot ca
03-Jan-2005 12:32
I really searched for a function that would do this as I've seen it in other languages but I couldn't find it here. This is particularily useful when combined with substr() to take the first part of a string up to a certain point.

strnpos() - Find the nth position of needle in haystack.

<?php

  
function strnpos($haystack, $needle, $occurance, $pos = 0) {
      
       for (
$i = 1; $i <= $occurance; $i++) {
          
$pos = strpos($haystack, $needle, $pos) + 1;
       }
       return
$pos - 1;
      
   }

?>

Example: Give me everything up to the fourth occurance of '/'.

<?php

   $haystack
= "/home/username/www/index.php";
  
$needle = "/";
  
  
$root_dir = substr($haystack, 0, strnpos($haystack, $needle, 4));
  
   echo
$root_dir;
  
?>

Returns: /home/username/www

Use this example with the server variable $_SERVER['SCRIPT_NAME'] as the haystack and you can self-discover a document's root directory for the purposes of locating global files automatically!
21-Dec-2004 12:31
In response to hackajar <matt> yahoo <trot> com,

No string-to-array function exists because it is not needed. If you reference a string with an offset like you do with an array, the character at that offset will be return. This is documented in section III.11's "Strings" article under the "String access and modification by character" heading.
andy a t onesandzeros d o t biz
10-Nov-2004 06:54
I use these little doo-dads quite a bit. I just thought I'd share them and maybe save someone a little time. No biggy. :)

// returns true if $str begins with $sub
function beginsWith( $str, $sub ) {
   return ( substr( $str, 0, strlen( $sub ) ) == $sub );
}

// return tru if $str ends with $sub
function endsWith( $str, $sub ) {
   return ( substr( $str, strlen( $str ) - strlen( $sub ) ) == $sub );
}

// trims off x chars from the front of a string
// or the matching string in $off is trimmed off
function trimOffFront( $off, $str ) {
   if( is_numeric( $off ) )
       return substr( $str, $off );
   else
       return substr( $str, strlen( $off ) );
}

// trims off x chars from the end of a string
// or the matching string in $off is trimmed off
function trimOffEnd( $off, $str ) {
   if( is_numeric( $off ) )
       return substr( $str, 0, strlen( $str ) - $off );
   else
       return substr( $str, 0, strlen( $str ) - strlen( $off ) );
}
[tab!]
28-Oct-2004 03:29
//
// string strtrmvistl(  string str, [int maxlen = 64],
//                      [bool right_justify = false],
//                      [string delimter = "<br>\n"])
//
// splits a long string into two chunks (a start and an end chunk)
// of a given maximum length and seperates them by a given delimeter.
// a second chunk can be right-justified within maxlen.
// may be used to 'spread' a string over two lines.
//

function strtrmvistl($str, $maxlen = 64, $right_justify = false, $delimter = "<br>\n") {
   if(($len = strlen($str = chop($str))) > ($maxlen = max($maxlen, 12))) {
       $newstr = substr($str, 0, $maxlen - 3);

       if($len > ($maxlen - 3)) {
           $endlen = min(($len - strlen($newstr)), $maxlen - 3);
           $newstr .= "..." . $delimter;

           if($right_justify)
               $newstr .= str_pad('', $maxlen - $endlen - 3, ' ');

           $newstr .= "..." . substr($str, $len - $endlen);
       }

       return($newstr);
   }

   return($str);
}
terry dot greenlaw at logicalshift dot com
12-Aug-2004 01:52
Here's a simpler "simplest" way to toggle through a set of 1..n colors for web backgrounds:

<?php
$colours
= array('#000000', '#808080', '#A0A0A0', '#FFFFFF');

// Get a colour
$color = next($colors) or $color = reset($colors);
?>

The code doesn't need to know anything about the number of elements being cycled through. That way you won't have to tracking down all the code when changing the number of colors or the color values.