php如何把一个数组中的键名合并到键值中？下面主要的代码：

<?php
$test = array("key1"=>"value1","key2"=>"value2","key3"=>"value3");
foreach($test as $key=>$value){
$test[$key] = $key.$value;
}
foreach($test as $key=>$value){
echo $key,":",$value,"<br/>";
}
?>

　　将输出

key1:key1value1
key2:key2value2
key3:key3value3