以下为引用的内容：

// 实在无聊,突发奇想,想把PHP里面部分已经提供封装好的函数重新使用PHP实现一遍,

// 于是便有了下面的代码主要实现了PHP中部分字符串处理函数,同时实现了一些PHP中

// 没有,但是同样有作用的字符串处理函数同样的这些函数,也能够使用其他语言来实

// 现,比如用C/VBScript/Perl等等,那么你就能够有一个自己的函数库.

// 以下函数不一定能够成功运行,只是为了学习而已。

//

// 如果无特别声明,全部是由于heiyeluren原创,要使用任何函数都请保留作者信息

/**

* String Functions Reconstruct

*

* Copyright (c) 2005 heiyeluren

* Author: heiyeluren

* $Id: StringFunctions.php,v 0.1 e 2005-5-29 23:21 heiyeluren Exp $

**/

// {{{ strlen()

/**

* Count string length

*

* @param string $str need count length string variable

* @return int return count result

* @version v0.1

* @create 2005-5-24

* @modified 2005-5-24

* @author heiyeluren

*/

function strlen1($str)

{

if ($str == '')

return 0;

$count = 0;

while (1)

{

if ($str[$count] != NULL)

{

$count++;

continue;

}

else

break;

}

return $count;

}

// }}}

// {{{ substr()

/**

* Get sub string

*

* @param string $str need get sub string variable

* @param int $start start get sub string

* @param int $length need get string length

* @return string return sub string

* @version v0.2

* @create 2005-5-24

* @modified 2005-5-25

* @author heiyeluren

*/

function substr1($str, $start, $length=0)

{

if ($str == '')

return;

if ($start > strlen($str))

return;

if (($length != NULL) && ($start > 0) && ($length > strlen($str)-$start))

return;

if (($length != NULL) && ($start < 0) && ($length > strlen($str)+$start))

return;

if ($length == NULL)

$length = (strlen($str) - $start);

if ($start < 0)

{

for ($i=(strlen($str)+$start); $i<(strlen($str)+$start+$length); $i++)

{

$substr .= $str[$i];

}

}

if ($length > 0)

{

for ($i=$start; $i<($start+$length); $i++)

{

$substr .= $str[$i];

}

}

if ($length < 0)

{

for ($i=$start; $i<(strlen($str)+$length); $i++)

{

$substr .= $str[$i];

}

}

return $substr;

}

// }}}

// {{{ strrev()

/**

* Reversal string order

*

* @param string $str need reversal string variable

* @return string reversal string

* @version v0.1 www.knowsky.com

* @create 2005-5-24

* @modified 2005-5-24

* @author heiyeluren

*/

function strrev1($str)

{

if ($str == '')

return 0;

for ($i=(strlen($str)-1); $i>=0; $i--)

{

$rev_str .= $str[$i];

}

return $rev_str;

}

// }}}

// {{{ strcmp()

/**

* String comparison

*

* @param string $s1 first string

* @param string $s2 second string

* @return int return -1,str1 < str2; return 1, str1 > str2, str1 = str2,

* return 0, other, return false

* @version v0.1

* @create 2005-5-24

* @modified 2005-5-24

* @author heiyeluren

*/

function strcmp1($s1, $s2)

{

if (strlen($s1) < strlen($s2))

return -1;

if (strlen($s1) > strlen($s2))

return 1;

for ($i=0; $i

{

if ($s1[$i] == $s2[$i])

continue;

else

return false;

}

return 0;

}

// }}}

// {{{ strchr(), strstr(), strpos()

/**

* Find first occurrence of a string

*

* @param string $str parent string

* @param string $substr need match sub string

* @return int return find sub string at parent string first place,

* f not find, return false

* @version v0.4

* @create 2005-5-24

* @modified 2005-5-29

* @author heiyeluren

*/

function strchr1($str, $substr)

{

$m = strlen($str);

$n = strlen($substr);

if ($m < $n)

return false;

for ($i=0; $i<=($m-$n+1); $i++)

{

$sub = substr($str, $i, $n);

if (strcmp($sub, $substr) == 0)

return $i;

}

return false;

}

// }}}

// {{{ str_replace()

/**

* Replace all occurrences of the search string with the replacement string

*

* @param string $substr need replace sub string variable

* @param string $newsubstr new sub string

* @param string $str operate parent string

* @return string return replace after new parent string

* @version v0.2

* @create 2005-5-24

* @modified 2005-5-29

* @author heiyeluren

*/

function str_replace1($substr, $newsubstr, $str)

{

$m = strlen($str);

$n = strlen($substr);

$x = strlen($newsubstr);

if (strchr($str, $substr) == false)

return false;

for ($i=0; $i<=($m-$n+1); $i++)

{

$i = strchr($str, $substr);

$str = str_delete($str, $i, $n);

$str = str_insert($str, $i, $newstr);

}

return $str;

}

// }}}

/************ 以下串处理函数是PHP中没有的，自己写着玩 ***************/

// {{{ insert_str(), delete_str(), index_str()

/**

* Basic string operate

*

* @param string $str need get sub string variable

* @param int $start start get sub string

* @param int $length need get string length

* @return string return sub string

* @version v0.1

* @create 2005-5-24

* @modified 2005-5-24

* @author heiyeluren

*/

function str_insert($str, $i, $substr)

{

for($j=0; $j<$i; $j++)

{

$startstr .= $str[$j];

}

for ($j=$i; $j

{

$laststr .= $str[$j];

}

$str = ($startstr . $substr . $laststr);

return $str;

}

function str_delete($str, $i, $j)

{

for ($c=0; $c<$i; $c++)

{

$startstr .= $str[$c];

}

for ($c=($i+$j); $c

{

$laststr .= $str[$c];

}

$str = ($startstr . $laststr);

return $str;

}

// }}}

// {{{ strcpy()

/**

* Use designate sub string replace string

*

* @param string $str need get sub string variable

* @param int $start start get sub string

* @param int $length need get string length

* @return string return sub string

* @version v0.1

* @create 2005-5-27

* @modified 2005-5-27

* @author heiyeluren

*/

function strcpy($s1, $s2)

{

if (strlen($s1) == NULL)

return;

if (!isset($s2))

return;

for ($i=0; $i

{

$s2[] = $s1[$i];

}

return $s2;

}

// }}}

// {{{ strcat()

/**

* Use designate sub string replace string

*

* @param string $str need get sub string variable

* @param int $start start get sub string

* @param int $length need get string length

* @return string return sub string

* @version v0.1

* @create 2005-5-27

* @modified 2005-5-27

* @author heiyeluren

*/

function strcat($s1, $s2)

{

if (!isset($s1))

return;

if (!isset($s2))

return;

$newstr = $s1 . $s2;

return $newsstr;

}

// }}}

// {{{ php_encode(), php_decode()

/**

* Simple string encode/decode function

*

* @param string $str need code/encode string variable

* @return string code/encode after string

* @version v0.2

* @create 2005-3-11

* @modified 2005-5-24

* @author heiyeluren

*/

/* String encode function */

function php_encode($str)

{

if ($str=='' && strlen($str)>128)

return false;

for($i=0; $i

{

$c = ord($str[$i]);

if ($c>31 && $c<107)

$c += 20;

if ($c>106 && $c<127)

$c -= 75;

$word = chr($c);

$s .= $word;

}

return $s;

}

/* String decode function */

function php_decode($str)

{

if ($str=='' && strlen($str)>128)

return false;

for($i=0; $i

{

$c = ord($word);

if ($c>106 && $c<127)

$c = $c-20;

if ($c>31 && $c<107)

$c = $c+75;

$word = chr($c);

$s .= $word;

}

return $s;

}

// }}}

// {{{ php_encrypt(), php_decrypt()

/**

* Simple string encrypt/decrypt function

*

* @param string $str need crypt string variable

* @return string encrypt/decrypt after string

* @version v0.1

* @create 2005-5-27

* @modified 2005-5-29

* @author heiyeluren

*/

/* define crypt key */

$encrypt_key = 'abcdefghijklmnopqrstuvwxyz1234567890';

$decrypt_key = 'ngzqtcobmuhelkpdawxfyivrsj2468021359';

/* String encrypt function */

function php_encrypt($str)

{

global $encrypt_key, $decrypt_key;

if (strlen($str) == 0)

return false;

for ($i=0; $i

{

for ($j=0; $j

{

if ($str[$i] == $encrypt_key[$j])

{

$enstr .= $decrypt_key[$j];

break;

}

}

}

return $enstr;

}

/* String decrypt function */

function php_decrypt($str)

{

global $encrypt_key, $decrypt_key;

if (strlen($str) == 0)

return false;

for ($i=0; $i

{

for ($j=0; $j

{

if ($str[$i] == $decrypt_key[$j])

{

$enstr .= $encrypt_key[$j];

break;

}

}

}

return $enstr;

}

// }}}