这个问题在这里已有答案：
我从多维数组中提取数据。使用foreach循环时，我感到困惑，无法从我的数组中提取数据。这是我的数组名为$ result_array：
Array
(
[0] => Array
(
[0] => Array
(
[category_id] => 19
[category_name] => Food
[publication_status] => 1
[deletion_status] => 1
)
[1] => Array
(
[category_id] => 16
[category_name] => Gourmet
[publication_status] => 1
[deletion_status] => 1
)
[2] => Array
(
[category_id] => 17
[category_name] => Islamic Product
[publication_status] => 1
[deletion_status] => 1
)
)
[1] => Array
(
[0] => Array
(
[category_id] => 28
[category_name] => Dry Food
[publication_status] => 1
[deletion_status] => 1
)
[1] => Array
(
[category_id] => 39
[category_name] => Testt
[publication_status] => 1
[deletion_status] => 1
)
[2] => Array
(
[category_id] => 37
[category_name] => Seasonal Items
[publication_status] => 1
[deletion_status] => 1
)
[3] => Array
(
[category_id] => 38
[category_name] => Icon Items
[publication_status] => 1
[deletion_status] => 1
)
)
[2] => Array
(
[0] => Array
(
[category_id] => 29
[category_name] => Biscuits
[publication_status] => 1
[deletion_status] => 1
)
)
[3] => Array
(
[0] => Array
(
[category_id] => 30
[category_name] => Nutty
[publication_status] => 1
[deletion_status] => 1
)
)
)
这是我的循环：
foreach($result_array as $info) {
echo $info['category_name'].'<br>';
}
这个循环给我一个错误，说明未定义索引category_name。我是这个领域的新手。谁能开导我？谢谢
你需要双重foreach，像这样：
foreach($result_array as $outer_array)
foreach($outer_array as $inner_array)
echo $inner_array['category_name'] . '<br>';
你循环的$result_array有4个元素，没有一个元素与密钥category_name有价值。你需要做双foreach或更聪明的东西。