当数组的父值是字符串而不是数组时，isset 在数组上返回 true
我的一个阵列遇到了一个奇怪的问题。数组看起来像这样，然后我对它执行 print_r() ：
Array
(
[id] => 1688
[pCid] => 1992
[category] => 177
[archive] => 0
[catid] =>
[pid] =>
[order_nr] => 1
[cOrder] => 1
[cSeo] => no-colour
[order_id] => 0
[price] => 8.99
[sale_price] => 7.99
[sale_expiry] =>
[oPrices] => 7.99
[member_price] => 6.99
[set] => 0
)
当我做一个简单的操作时
if(isset($array['set']['stock'])){}
，当 $array['set'] 当前等于 0 时，它返回 true。
var_dump(isset($array['set']['stock'])) //bool(true)
返回 true
任何想法为什么会发生这种情况？
（我通过执行 is_array($array['set']) 检查解决了检查问题，但仍然不确定为什么 isset 不起作用）
我注意到您可以像这样复制相同的问题：
<?php
$colour = array();
$colour['set'] = '0';
var_dump(isset($colour['set']['stock'])); //will return true
?>
I encountered a strange issue with one of my arrays. The array looks like this then I do a print_r() on it:
Array
(
[id] => 1688
[pCid] => 1992
[category] => 177
[archive] => 0
[catid] =>
[pid] =>
[order_nr] => 1
[cOrder] => 1
[cSeo] => no-colour
[order_id] => 0
[price] => 8.99
[sale_price] => 7.99
[sale_expiry] =>
[oPrices] => 7.99
[member_price] => 6.99
[set] => 0
)
and when I do a simmple
if(isset($array['set']['stock'])){}
it returns true when the $array['set'] currentlly equals 0.
var_dump(isset($array['set']['stock'])) //bool(true)
returns true
Any ideas why is this happening?
(I resolved the check issue by doing is_array($array['set']) check but still not sure why is the isset not working)
I noticed that you can replicate the same issue like this:
<?php
$colour = array();
$colour['set'] = '0';
var_dump(isset($colour['set']['stock'])); //will return true
?>
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字符串是字符数组。当比较 ['stock'] 数组时，它会比较第一个字符，因为它正在查看字符串。
例如返回“f”。
An string is an array of characters. When the ['stock'] array is compared it compares the first character as it's looking at a string.
Returns 'f' for example.
在 PHP 中（与大多数其他语言一样），字符串可以作为字符数组进行访问。
因此，当您执行
$str['stock']时，您实际上正在访问$str中的'stock'偏移量。由于字符串只有数字偏移量，因此字符串'stock'被转换为整数，并且由于它不包含任何数字，因此结果为0。因此，您可以访问$str[0]，它是已设置的字符串的第一个字符。In PHP (as in most other languages) strings can be accessed as arrays of characters.
So when you do
$str['stock']you really are accessing the'stock'offset in the$str. As strings have only numeric offsets the string'stock'is cast to an integer and as it doesn't contain any numbers the result is0. Thus you access$str[0], which is the first character of the string, which is set.isset() 检查特定变量或数组元素是否存在。包含任何内容（包括
null或0）的变量/元素仍然会被设置，因为它存在。如果要检查非零内容，请使用empty()代替，如果变量存在但包含''、null，则返回 true、0、'0'等...但是，您仍然需要进行 isset 测试，因为 empty() 会触发“ no such array key”如果您尝试在确实不存在的数组键上运行它，则会发出警告。isset() checks if a particular variable or array element exists. A variable/element that contains ANYTHING, including a
nullor a0is still set, because it exists. If you want to check for non-zero contents, then useempty()instead, which will come back true if the variable exists but contains'',null,0,'0', etc... However, you'd still need to do an isset test, as empty() will trigger a "no such array key" warning if you attempt to run it on an array key which truly does not exist.