提交页面 shorten.php：

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<form method="post" action="show.php">
	<input type="text" name="url" value="" style="width:800px;padding:3px 7px;" /> 
	<input type="submit" name="submit" value="Shorten Url" />
</form>

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处理页面 show.php：

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<?php
include 'functions.php';
include 'shorturls.php';

$entry = $_POST['submit'];
$url = $_POST['url'];
$output = '';

if($entry == 'Shorten Url' AND $url)
{
	if(!in_array($url,$shortUrls))
	{
		$uif = alphaID(count($shortUrls),false,6);
		
		if(!array_key_exists($uif,$shortUrls))
		{
			$shortUrls[$uif] = $url;
						
			$file = fopen('shorturls.php','w'); 
			fwrite($file,'<?php $shortUrls = ' . var_export($shortUrls,true) . ';?>');
			fclose($file);
			$output = 'Original Url : '.$url.'<br> Shorten Ulr : <a href="http://www.yourdomain.com/api/s='.$uif.'" target="_blank">http://www.yourdomain.com/api/s='.$uif.'</a>';
		}
		else $output = 'access error';
	}
	else
	{
		$uif = array_search($url,$shortUrls);
		$output =  'Original Url : '.$url.'<br> Shorten Ulr : <a href="http://www.yourdomain.com/api/s='.$uif.'" target="_blank">http://www.yourdomain.com/api/s='.$uif.'</a>';
	}
	
	echo $output.'<br><br> <a href="shorten.php">Back</a>';

}
?>

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关联页面?functions.php

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<?php 
function alphaID($in, $to_num = false, $pad_up = false, $passKey = null)
{
	$index = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	if ($passKey !== null) {
		// Although this function's purpose is to just make the
		// ID short - and not so much secure,
		// with this patch by Simon Franz (http://blog.snaky.org/)
		// you can optionally supply a password to make it harder
		// to calculate the corresponding numeric ID

		for ($n = 0; $n<strlen($index); $n++) $i[] = substr( $index,$n ,1);

		$passhash = hash('sha256',$passKey);
		$passhash = (strlen($passhash) < strlen($index))
			? hash('sha512',$passKey)
			: $passhash;

		for ($n=0; $n < strlen($index); $n++) $p[] =  substr($passhash, $n ,1);

		array_multisort($p,  SORT_DESC, $i);
		$index = implode($i);
	}

	$base  = strlen($index);

	if ($to_num) {
		// Digital number  <<--  alphabet letter code
		$in  = strrev($in);
		$out = 0;
		$len = strlen($in) - 1;
		for ($t = 0; $t <= $len; $t++) {
			$bcpow = bcpow($base, $len - $t);
			$out   = $out + strpos($index, substr($in, $t, 1)) * $bcpow;
		}

		if (is_numeric($pad_up)) {
			$pad_up--;
			if ($pad_up > 0) $out -= pow($base, $pad_up);
		}
		$out = sprintf('%F', $out);
		$out = substr($out, 0, strpos($out, '.'));
	} 
	else 
	{
		// Digital number  -->>  alphabet letter code
		if (is_numeric($pad_up)) {
			$pad_up--;
			if ($pad_up > 0) $in += pow($base, $pad_up);
		}

		$out = "";
		for ($t = floor(log($in, $base)); $t >= 0; $t--) {
			$bcp = bcpow($base, $t);
			$a   = floor($in / $bcp) % $base;
			$out = $out . substr($index, $a, 1);
			$in  = $in - ($a * $bcp);
		}
		$out = strrev($out); // reverse
	}

	return $out;
}
?>

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关联页面?shorturls.php

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<?php $shortUrls = array ();?>

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原理： 将提交的网址存放数组里面，同时为之产生一个唯一的键，之后将该数组存放文本中，当然你也可以存放到数据库中，此实例为存放到文本中。

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一些函数的解释：

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1. array_search() 函数

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array_search(value,array,strict)

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array_search() 函数与 in_array() 一样，在数组中查找一个键值。如果找到了该值，匹配元素的键名会被返回。如果没找到，则返回 false。

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2.?var_export()?函数

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此函数返回关