原始数组如下：
Array
(
[Danmark] => Country Object
(
[id:protected] => 39
[name:protected] => Danmark
[code:protected] => DK
[stringIndex:protected] => DENMARK
)
[Tyskland] => Country Object
(
[id:protected] => 59
[name:protected] => Tyskland
[code:protected] => DE
[stringIndex:protected] => GERMANY
)
[Irland] => Country Object
(
[id:protected] => 78
[name:protected] => Irland
[code:protected] => IE
[stringIndex:protected] => IRELAND
)
[Italien] => Country Object
(
[id:protected] => 81
[name:protected] => Italien
[code:protected] => IT
[stringIndex:protected] => ITALY
)
[Holland] => Country Object
(
[id:protected] => 119
[name:protected] => Holland
[code:protected] => NL
[stringIndex:protected] => NETHERLANDS
)
[Nya Zeeland] => Country Object
(
[id:protected] => 122
[name:protected] => Nya Zeeland
[code:protected] => NZ
[stringIndex:protected] => NEW_ZEALAND
)
[Polen] => Country Object
(
[id:protected] => 138
[name:protected] => Polen
[code:protected] => PL
[stringIndex:protected] => POLAND
)
[Spanien] => Country Object
(
[id:protected] => 161
[name:protected] => Spanien
[code:protected] => ES
[stringIndex:protected] => SPAIN
)
[Sverige] => Country Object
(
[id:protected] => 166
[name:protected] => Sverige
[code:protected] => SE
[stringIndex:protected] => SWEDEN
)
[Schweiz] => Country Object
(
[id:protected] => 167
[name:protected] => Schweiz
[code:protected] => CH
[stringIndex:protected] => SWITZERLAND
)
[England] => Country Object
(
[id:protected] => 185
[name:protected] => England
[code:protected] => GB
[stringIndex:protected] => UNITED_KINGDOM
)
[Osterrike] => Country Object
(
[id:protected] => 197
[name:protected] => Osterrike
[code:protected] => AT
[stringIndex:protected] => AUSTRIA
)
[Belgien] => Country Object
(
[id:protected] => 236
[name:protected] => Belgien
[code:protected] => BE
[stringIndex:protected] => BELGIUM
)
)
我打电话后：
ksort($countries, SORT_STRING);
我得到这个：
Array
(
[Osterrike] => Country Object
(
[id:protected] => 197
[name:protected] => Osterrike
[code:protected] => AT
[stringIndex:protected] => AUSTRIA
)
[Belgien] => Country Object
(
[id:protected] => 236
[name:protected] => Belgien
[code:protected] => BE
[stringIndex:protected] => BELGIUM
)
[Danmark] => Country Object
(
[id:protected] => 39
[name:protected] => Danmark
[code:protected] => DK
[stringIndex:protected] => DENMARK
)
[Tyskland] => Country Object
(
[id:protected] => 59
[name:protected] => Tyskland
[code:protected] => DE
[stringIndex:protected] => GERMANY
)
[Irland] => Country Object
(
[id:protected] => 78
[name:protected] => Irland
[code:protected] => IE
[stringIndex:protected] => IRELAND
)
[Italien] => Country Object
(
[id:protected] => 81
[name:protected] => Italien
[code:protected] => IT
[stringIndex:protected] => ITALY
)
[Holland] => Country Object
(
[id:protected] => 119
[name:protected] => Holland
[code:protected] => NL
[stringIndex:protected] => NETHERLANDS
)
[Nya Zeeland] => Country Object
(
[id:protected] => 122
[name:protected] => Nya Zeeland
[code:protected] => NZ
[stringIndex:protected] => NEW_ZEALAND
)
[Polen] => Country Object
(
[id:protected] => 138
[name:protected] => Polen
[code:protected] => PL
[stringIndex:protected] => POLAND
)
[Spanien] => Country Object
(
[id:protected] => 161
[name:protected] => Spanien
[code:protected] => ES
[stringIndex:protected] => SPAIN
)
[Sverige] => Country Object
(
[id:protected] => 166
[name:protected] => Sverige
[code:protected] => SE
[stringIndex:protected] => SWEDEN
)
[Schweiz] => Country Object
(
[id:protected] => 167
[name:protected] => Schweiz
[code:protected] => CH
[stringIndex:protected] => SWITZERLAND
)
[England] => Country Object
(
[id:protected] => 185
[name:protected] => England
[code:protected] => GB
[stringIndex:protected] => UNITED_KINGDOM
)
)
当我使用相同的索引来测试它，但使用简单字符串的值而不是Country对象时，它会正确排序。当我用相同的索引测试它，但用空的Test对象而不是我的Country对象时，它再次正确排序。但在这种特殊情况下，它返回了错误的结果。它们也没有按照对象内的任何值进行排序，所有值看起来都是随机的。
Country类非常简单：
class Country {
protected $id;
protected $name;
protected $code;
protected $stringIndex;
}
原因是什么？
作为回复发布，因为这作为评论会非常难看：
我不能复制你的O先到：
代码：
<?php
$foo = array(
'P' => 'regular p',
'Ö' => 'umlaut o',
'O' => 'regular o',
'A' => 'regular A'
);
var_dump（$foo）；ksort（$foo）；var_dump（$foo）；
结果：
array(4) {
["P"]=>
string(9) "regular p"
["Ö"]=>
string(8) "umlaut o"
["O"]=>
string(9) "regular o"
["A"]=>
string(9) "regular A"
}
array(4) {
["A"]=>
string(9) "regular A"
["O"]=>
string(9) "regular o"
["P"]=>
string(9) "regular p"
["Ö"]=>
string(8) "umlaut o"
}
正如您所看到的，Ö确实排序不正确，但它排序到数组的END，而不是开头。
我想我的答案太晚了，但数组似乎已经按照Country Object的stringIndex字段进行了排序。
也许（只是也许，我不知道确切的原因）因为SORT_STRING标志，ksort尝试填充具有定义的string类型的元素，但如果不能，那么它会尝试在Country对象中查找具有"字符串"关键字的键，如stringIndex。