php 数组比较大小

今天用到个数组排序，里边有两个key，但是对应值不一样，居然能直接比较大小

比如

array("key1"=>1,"key2"=>2)  >  array("key1"=>1,"key2"=>3) ? "1" : "0"  输出0

array("key1"=>1,"key2"=>4)  >  array("key1"=>1,"key2"=>3) ? "1" : "0"  输出1

array("key1"=>1,"key3"=>2)  >  array("key1"=>1,"key2"=>3) ? "1" : "0"  输出0

array("key1"=>2,"key3"=>2)  >  array("key1"=>1,"key2"=>3) ? "1" : "0"  输出1

发现：php数组比较大小，会比较数组相同key名对应的值。