<?php
$words = array(".NET"=>"Microsoft","JAVA"=>"SUN","JSP"=>"SUN");
$searchKey1 = array_search("SUN",$words);
var_dump($searchKey1);//输出：string(4) "JAVA" 
echo "<br/>";
$searchKey2 = array_search("microsoft",$words);
var_dump($searchKey2);//输出：bool(false) 
echo "<br/>";

$numbers = array("PI"=>"3.14","直角"=>"90");
$searchKey3 = array_search(90,$numbers);
$searchKey4 = array_search(90,$numbers,TRUE);
var_dump($searchKey3);//输出：string(4) "直角" 
echo "<br/>";
var_dump($searchKey4);//输出：bool(false) 
?>