php怎么实现数组转json

string json_encode ( $value [, $options = 0 ] )

$array_1 = array(); //一维数组
	$array_2 = array(); //多维数组
	$array_1['username']='ericwolf';
	$array_1['age']=25;
 
	$array_2['menber']['aa']['username']='ericwolf';
	$array_2['menber']['aa']['age']=25;
	$array_2['menber']['bb']['username']='eeee';
	$array_2['menber']['bb']['age']=22;
 
	print_r($array_2);
	$jsonObj_1 = json_encode($array_1);
	$jsonObj_1 = json_encode($array_2);