字符串 函数

参见

更多强大的字符串处理函数，参见 POSIX 正则表达式函数和 Perl 兼容正则表达式函数。

Table of Contents

  • addcslashes — 以 C 语言风格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 — 函数把包含数据的二进制字符串转换为十六进制值
  • chop — rtrim 的别名
  • 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 — 解码一个 uuencode 编码的字符串
  • convert_uuencode — 使用 uuencode 编码一个字符串
  • 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 — 单向字符串散列
  • echo — 输出一个或多个字符串
  • explode — 使用一个字符串分割另一个字符串
  • fprintf — 将格式化后的字符串写入到流
  • get_html_translation_table — 返回使用 htmlspecialchars 和 htmlentities 后的转换表
  • hebrev — 将逻辑顺序希伯来文（logical-Hebrew）转换为视觉顺序希伯来文（visual-Hebrew）
  • hebrevc — 将逻辑顺序希伯来文（logical-Hebrew）转换为视觉顺序希伯来文（visual-Hebrew），并且转换换行符
  • hex2bin — 转换十六进制字符串为二进制字符串
  • html_entity_decode — Convert all HTML entities to their applicable characters
  • htmlentities — 将字符转换为 HTML 转义字符
  • htmlspecialchars_decode — 将特殊的 HTML 实体转换回普通字符
  • htmlspecialchars — 将特殊字符转换为 HTML 实体
  • implode — 将一个一维数组的值转化为字符串
  • join — 别名 implode
  • lcfirst — 使一个字符串的第一个字符小写
  • levenshtein — 计算两个字符串之间的编辑距离
  • localeconv — Get numeric formatting information
  • ltrim — 删除字符串开头的空白字符（或其他字符）
  • md5_file — 计算指定文件的 MD5 散列值
  • md5 — 计算字符串的 MD5 散列值
  • metaphone — Calculate the metaphone key of a string
  • money_format — 将数字格式化成货币字符串
  • nl_langinfo — Query language and locale information
  • nl2br — 在字符串所有新行之前插入 HTML 换行标记
  • number_format — 以千位分隔符方式格式化一个数字
  • ord — 返回字符的 ASCII 码值
  • parse_str — 将字符串解析成多个变量
  • print — 输出字符串
  • printf — 输出格式化字符串
  • quoted_printable_decode — 将 quoted-printable 字符串转换为 8-bit 字符串
  • quoted_printable_encode — 将 8-bit 字符串转换成 quoted-printable 字符串
  • quotemeta — 转义元字符集
  • rtrim — 删除字符串末端的空白字符（或者其他字符）
  • setlocale — 设置地区信息
  • sha1_file — 计算文件的 sha1 散列值
  • sha1 — 计算字符串的 sha1 散列值
  • similar_text — 计算两个字符串的相似度
  • soundex — Calculate the soundex key of a string
  • sprintf — Return a formatted string
  • sscanf — 根据指定格式解析输入的字符
  • str_getcsv — 解析 CSV 字符串为一个数组
  • str_ireplace — str_replace 的忽略大小写版本
  • str_pad — 使用另一个字符串填充字符串为指定长度
  • str_repeat — 重复一个字符串
  • str_replace — 子字符串替换
  • str_rot13 — 对字符串执行 ROT13 转换
  • str_shuffle — 随机打乱一个字符串
  • str_split — 将字符串转换为数组
  • str_word_count — 返回字符串中单词的使用情况
  • strcasecmp — 二进制安全比较字符串（不区分大小写）
  • strchr — 别名 strstr
  • strcmp — 二进制安全字符串比较
  • strcoll — 基于区域设置的字符串比较
  • strcspn — 获取不匹配遮罩的起始子字符串的长度
  • strip_tags — 从字符串中去除 HTML 和 PHP 标记
  • stripcslashes — 反引用一个使用 addcslashes 转义的字符串
  • stripos — 查找字符串首次出现的位置（不区分大小写）
  • stripslashes — 反引用一个引用字符串
  • stristr — strstr 函数的忽略大小写版本
  • strlen — 获取字符串长度
  • strnatcasecmp — 使用“自然顺序”算法比较字符串（不区分大小写）
  • strnatcmp — 使用自然排序算法比较字符串
  • strncasecmp — 二进制安全比较字符串开头的若干个字符（不区分大小写）
  • strncmp — 二进制安全比较字符串开头的若干个字符
  • strpbrk — 在字符串中查找一组字符的任何一个字符
  • strpos — 查找字符串首次出现的位置
  • strrchr — 查找指定字符在字符串中的最后一次出现
  • strrev — 反转字符串
  • strripos — 计算指定字符串在目标字符串中最后一次出现的位置（不区分大小写）
  • strrpos — 计算指定字符串在目标字符串中最后一次出现的位置
  • strspn — 计算字符串中全部字符都存在于指定字符集合中的第一段子串的长度。
  • strstr — 查找字符串的首次出现
  • strtok — 标记分割字符串
  • strtolower — 将字符串转化为小写
  • strtoupper — 将字符串转化为大写
  • strtr — 转换指定字符
  • substr_compare — 二进制安全比较字符串（从偏移位置比较指定长度）
  • substr_count — 计算字串出现的次数
  • substr_replace — 替换字符串的子串
  • substr — 返回字符串的子串
  • trim — 去除字符串首尾处的空白字符（或者其他字符）
  • ucfirst — 将字符串的首字母转换为大写
  • ucwords — 将字符串中每个单词的首字母转换为大写
  • vfprintf — 将格式化字符串写入流
  • vprintf — 输出格式化字符串
  • vsprintf — 返回格式化字符串
  • wordwrap — 打断字符串为指定数量的字串

User Contributed Notes

str at maphpia dot com 04-Jul-2013 05:19
I was looking for a function to find the common substring in 2 different strings. I tried both the mb_string_intersect and string_intersect functions listed here but didn't work for me. I found the algorithm at http://en.wikibooks.org/wiki/Algorithm_implementation/Strings/Longest_common_substring#PHP so here I post you the function

<?php

/**
 * Finds the matching string between 2 strings
 *
 * @param string $string1
 * @param string $string2
 * @param number $minChars
 *
 * @return NULL|string
 *
 * @link http://en.wikibooks.org/wiki/Algorithm_implementation/Strings/Longest_common_substring#PHP
 */
function string_intersect($string_1, $string_2)
{
    $string_1_length = strlen($string_1);
    $string_2_length = strlen($string_2);
    $return          = "";

    if ($string_1_length === 0 || $string_2_length === 0) {
        // No similarities
        return $return;
    }

    $longest_common_subsequence = array();

    // Initialize the CSL array to assume there are no similarities
    for ($i = 0; $i < $string_1_length; $i++) {
        $longest_common_subsequence[$i] = array();
        for ($j = 0; $j < $string_2_length; $j++) {
            $longest_common_subsequence[$i][$j] = 0;
        }
    }

    $largest_size = 0;

    for ($i = 0; $i < $string_1_length; $i++) {
        for ($j = 0; $j < $string_2_length; $j++) {
            // Check every combination of characters
            if ($string_1[$i] === $string_2[$j]) {
                // These are the same in both strings
                if ($i === 0 || $j === 0) {
                    // It's the first character, so it's clearly only 1 character long
                    $longest_common_subsequence[$i][$j] = 1;
                } else {
                    // It's one character longer than the string from the previous character
                    $longest_common_subsequence[$i][$j] = $longest_common_subsequence[$i - 1][$j - 1] + 1;
                }

                if ($longest_common_subsequence[$i][$j] > $largest_size) {
                    // Remember this as the largest
                    $largest_size = $longest_common_subsequence[$i][$j];
                    // Wipe any previous results
                    $return       = "";
                    // And then fall through to remember this new value
                }

                if ($longest_common_subsequence[$i][$j] === $largest_size) {
                    // Remember the largest string(s)
                    $return = substr($string_1, $i - $largest_size + 1, $largest_size);
                }
            }
            // Else, $CSL should be set to 0, which it was already initialized to
        }
    }

    // Return the list of matches
    return $return;
}
Tomek Rychtyk 09-Feb-2012 06:58
Get the intersection of two strings using array_intersect

<?php

function string_intersect($string1, $string2)
{
    $array1 = $array2 = array();

    for($i = 0, $j = 0, $s1_len = strlen($string1), $s2_len = strlen($string2);($i < $s1_len) || ($j < $s2_len); $i++, $j++) {
        if($i < $s1_len) {
            $array1[] = $string1[$i];
        }
        if($j < $s2_len) {
            $array2[] = $string2[$j];
        }
    }

    return implode('', array_intersect($array1, $array2));
}

?>

For more advanced comparison you can use array_uintersect as well.
Stephen Dewey 20-Nov-2008 02:33
If you want a function to return all text in a string up to the Nth occurrence of a substring, try the below function.

Works in PHP >= 5.

(Pommef provided another sample function for this purpose below, but I believe it is incorrect.)

<?php

// Returns all of $haystack up to (but excluding) the $n_occurrence occurrence of $needle. Therefore:
//        If there are < $n_occurrence occurrences of $needle in $haystack, the entire string will be returned.
//        If there are >= $n_occurrence occurrences of $needle in $haystack, the returned string will end before the $n_occurrence'th needle.
// This function only makes sense for $n_occurrence >= 1
function nsubstr($needle, $haystack, $n_occurrence)
{
    // After exploding by $needle, every entry in $arr except (possibly) part of the last entry should have its content returned.
    $arr = explode($needle,$haystack,$n_occurrence);
    // Examine last entry in $arr. If it contains $needle, cut out all text except for the text before $needle.
    $last = count($arr) - 1;
    $pos_in_last = strpos($arr[$last],$needle);
   
    if ($pos_in_last !== false)
        $arr[$last] = substr($arr[$last],0,$pos_in_last);
   
    return implode($needle,$arr);
}

$string = 'd24jkdslgjldk2424jgklsjg24jskgldjk24';

print 'S:  ' . $string . '<br>';
print '1: ' . nsubstr('24',$string,1) . '<br>';
print '2: ' . nsubstr('24',$string,2) . '<br>';
print '3: ' . nsubstr('24',$string,3) . '<br>';
print '4: ' . nsubstr('24',$string,4) . '<br>';
print '5: ' . nsubstr('24',$string,5) . '<br>';
print '6: ' . nsubstr('24',$string,6) . '<br>';
print '7: ' . nsubstr('24',$string,7) . '<br>';

/*
// prints:
S: d24jkdslgjldk2424jgklsjg24jskgldjk24
1: d
2: d24jkdslgjldk
3: d24jkdslgjldk24
4: d24jkdslgjldk2424jgklsjg
5: d24jkdslgjldk2424jgklsjg24jskgldjk
6: d24jkdslgjldk2424jgklsjg24jskgldjk24
7: d24jkdslgjldk2424jgklsjg24jskgldjk24
*/

?>

Note that this function can be combined with wordwrap() to accomplish a routine but fairly difficult web design goal, namely, limiting inline HTML text to a certain number of lines. wordwrap() can break your string using <br>, and then you can use this function to only return text up to the N'th <br>.

You will still have to make a conservative guess of the max number of characters per line with wordwrap(), but you can be more precise than if you were simply truncating a multiple-line string with substr().

See example:

<?php

$text = 'Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Pellentesque id massa. Duis sollicitudin ipsum vel diam. Aliquam pulvinar sagittis felis. Nullam hendrerit semper elit. Donec convallis mollis risus. Cras blandit mollis turpis. Vivamus facilisis, sapien at tincidunt accumsan, arcu dolor suscipit sem, tristique convallis ante ante id diam. Curabitur mollis, lacus vel gravida accumsan, enim quam condimentum est, vitae rutrum neque magna ac enim.';

$wrapped_text = wordwrap($text,100,'<br>',true);

$three_lines = nsubstr('<br>',$wrapped_text,3);

print '<br><br>' . $three_lines;

$four_lines = nsubstr('<br>',$wrapped_text,4);

print '<br><br>' . $four_lines;

/*
prints:

Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Pellentesque id massa. Duis sollicitudin
ipsum vel diam. Aliquam pulvinar sagittis felis. Nullam hendrerit semper elit. Donec convallis
mollis risus. Cras blandit mollis turpis. Vivamus facilisis, sapien at tincidunt accumsan, arcu

Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Pellentesque id massa. Duis sollicitudin
ipsum vel diam. Aliquam pulvinar sagittis felis. Nullam hendrerit semper elit. Donec convallis
mollis risus. Cras blandit mollis turpis. Vivamus facilisis, sapien at tincidunt accumsan, arcu
dolor suscipit sem, tristique convallis ante ante id diam. Curabitur mollis, lacus vel gravida

*/

?>
Verdauga 20-Mar-2008 03:06
Just a note in regards to bloopletech a few posts down:

The word "and" should not be used when converting numbers to text.  "And" (at least in US English) should only be used to indicate the decimal place.

Example:
1,796,706 => one million, seven hundred ninety-six thousand, seven hundred six.
594,359.34 => five hundred ninety four thousand, three hundred fifty nine and thirty four hundredths
m 27-Jul-2007 02:10
Regarding the code for the function beginsWith($str, $sub), I found that it has problems when only one character is present after the string searched for. I found that this works better instead:

<?php
function beginsWith($str, $sub) {
    return (strncmp($str, $sub, strlen($sub)) == 0);
}
?>
mike &#34;eyes&#34; moe 18-Jun-2007 02:59
Here is a truly random string generator it uses the most common string functions it will work on anywhere.

<?php
    function random_string($max = 20){
        $chars = explode(" ", "a b c d e f g h i j k l m n o p q r s t u v w x y z 0 1 2 3 4 5 6 7 8 9");
        for($i = 0; $i < $max; $i++){
            $rnd = array_rand($chars);
            $rtn .= base64_encode(md5($chars[$rnd]));
        }
        return substr(str_shuffle(strtolower($rtn)), 0, $max);
    }
?>
admin at rotarymulundeast dot org 30-Jul-2006 12:16
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...
administrador(ensaimada)sphoera(punt)com 02-Mar-2006 03:10
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 24-Feb-2006 08:00
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 03:24
stripos for PHP4.x

<?php
  function stripos($haystack,$needle) {
    return strpos(strtoupper($haystack),strtoupper($needle));
  }
?>
admin at fivestarbuy dot com 21-Oct-2005 06:18
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 12:27
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
webmaster at cafe-clope dot net 14-Aug-2005 01:40
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 14-Jun-2005 07:38
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 05-Jun-2005 08:41
<?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 27-May-2005 07:45
<?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 03:34
<?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 19-Mar-2005 10:15
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 02-Jan-2005 05:32
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 05:31
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 09-Nov-2004 11:54
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!] 27-Oct-2004 09:29
//
// 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 07:52
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.