json_encode 出来的字符串只有花括号{}没有中括号[]

Question

$a = array("f"=>"sadf","k"=>array("a"=>"sadfg","b"=>array("e"=>"frg")),"j"=>array("c"=>"gver","d"=>array("i"=>32)));
$a = json_encode($a);
echo $a;
输出为
{"f":"sadf","k":{"a":"sadfg","b":{"e":"frg"}},"j":{"c":"gver","d":{"i":32}}}
请问[]哪里去了
在火狐firebug里也有时候不出现json选项

Answer 1

字母索引的数组的就是花括号，数字索引才是中括号，比如：

$arr = array(array('a'=>1,'b'=>2),array('c'=>3));
echo json_encode($arr);// hi-docs.com/php/json_encode.html