Php 我的usort代码工作不正常

我对该数组排序有问题：

Array
(
    [0] => stdClass Object
        (
            [id] => 120
            [registration_date] => 2012-10-19 16:57:46
            [username] => Jeff
        )
    [1] => stdClass Object
        (
            [id] => 121
            [registration_date] => 2012-12-23 16:57:46
            [username] => Peter
        )
    [2] => stdClass Object
        (
            [id] => 122
            [registration_date] => 2012-11-30 16:57:46
            [username] => Susan
        )

)

它存储在变量中：

$unsorted_users

我想在注册日期之前订购此阵列，如下所示：

Array
    (
        [0] => stdClass Object
            (
                [id] => 121
                [registration_date] => 2012-12-23 16:57:46
                [username] => Peter

            )
        [1] => stdClass Object
            (
                [id] => 122
                [registration_date] => 2012-11-30 16:57:46
                [username] => Susan

            )
        [2] => stdClass Object
            (
                [id] => 120
                [registration_date] => 2012-10-19 16:57:46
                [username] => Jeff
            )

    )

<?php

//  setup
$unsorted_users = array();

$t = new stdClass(); 
$t->id = 120; $t->username = 'jeff'; $t->registration_date = '2012-10-19 16:57:46'; 
$unsorted_users[] = $t;

$t = new stdClass(); 
$t->id = 121; $t->username = 'Peter'; $t->registration_date = '2012-12-23 16:57:46'; 
$unsorted_users[] = $t;

$t = new stdClass(); 
$t->id = 122; $t->username = 'Susan'; $t->registration_date = '2012-11-30 16:57:46'; 
$unsorted_users[] = $t;
// end setup


$sorted_users =    // this var is nor relevant as it shoud be allways true
usort($unsorted_users, function($a, $b) {
   return strcmp ($a->registration_date, $b->registration_date) ;
});

echo '<pre>';
print_r($unsorted_users)   // that is in fact ordered!

?>

按注册日期排序，如：

2012-12-23 16:57:46
2012-11-30 16:57:46
2012-10-19 16:57:46

而不是原来的样子：

2012-10-19 16:57:46
2012-12-23 16:57:46
2012-11-30 16:57:46

我正在使用这段代码，但效果不好（print\r（$sorted\u users）；输出$sorted\u users是“1”。我不知道为什么它是1而不是排序数组。）

---

有什么建议吗？

usort

正在通过引用处理数组，并返回成功布尔值-因此您的

$sorted\u用户

包含该布尔值。现在应该对原始数组进行排序

usort

正在通过引用处理数组，并返回成功布尔值-因此您的

$sorted\u users

包含该布尔值。现在应该对原始数组进行排序

你不能减去（那个）字符串。如果要比较两个字符串，请按如下方式使用strcmp（）函数：

Array
    (
        [0] => stdClass Object
            (
                [id] => 121
                [registration_date] => 2012-12-23 16:57:46
                [username] => Peter

            )
        [1] => stdClass Object
            (
                [id] => 122
                [registration_date] => 2012-11-30 16:57:46
                [username] => Susan

            )
        [2] => stdClass Object
            (
                [id] => 120
                [registration_date] => 2012-10-19 16:57:46
                [username] => Jeff
            )

    )

<?php

//  setup
$unsorted_users = array();

$t = new stdClass(); 
$t->id = 120; $t->username = 'jeff'; $t->registration_date = '2012-10-19 16:57:46'; 
$unsorted_users[] = $t;

$t = new stdClass(); 
$t->id = 121; $t->username = 'Peter'; $t->registration_date = '2012-12-23 16:57:46'; 
$unsorted_users[] = $t;

$t = new stdClass(); 
$t->id = 122; $t->username = 'Susan'; $t->registration_date = '2012-11-30 16:57:46'; 
$unsorted_users[] = $t;
// end setup


$sorted_users =    // this var is nor relevant as it shoud be allways true
usort($unsorted_users, function($a, $b) {
   return strcmp ($a->registration_date, $b->registration_date) ;
});

echo '<pre>';
print_r($unsorted_users)   // that is in fact ordered!

?>

拨弄，拨弄你不能删减字符串。如果要比较两个字符串，请按如下方式使用strcmp（）函数：

Array
    (
        [0] => stdClass Object
            (
                [id] => 121
                [registration_date] => 2012-12-23 16:57:46
                [username] => Peter

            )
        [1] => stdClass Object
            (
                [id] => 122
                [registration_date] => 2012-11-30 16:57:46
                [username] => Susan

            )
        [2] => stdClass Object
            (
                [id] => 120
                [registration_date] => 2012-10-19 16:57:46
                [username] => Jeff
            )

    )

<?php

//  setup
$unsorted_users = array();

$t = new stdClass(); 
$t->id = 120; $t->username = 'jeff'; $t->registration_date = '2012-10-19 16:57:46'; 
$unsorted_users[] = $t;

$t = new stdClass(); 
$t->id = 121; $t->username = 'Peter'; $t->registration_date = '2012-12-23 16:57:46'; 
$unsorted_users[] = $t;

$t = new stdClass(); 
$t->id = 122; $t->username = 'Susan'; $t->registration_date = '2012-11-30 16:57:46'; 
$unsorted_users[] = $t;
// end setup


$sorted_users =    // this var is nor relevant as it shoud be allways true
usort($unsorted_users, function($a, $b) {
   return strcmp ($a->registration_date, $b->registration_date) ;
});

echo '<pre>';
print_r($unsorted_users)   // that is in fact ordered!

?>

---

fiddle

已经有一些有效的答案，但要补充一下：

变量包含在对象中，而不是数组中；您有一个要排序的对象数组，因此应使用：

$a['registration_date']

而不是：

---

已经有一些有效的答案，但要补充：

变量包含在对象中，而不是数组中；您有一个要排序的对象数组，因此应使用：

$a['registration_date']

而不是：

---

我得到这个错误：致命错误：无法将stdClass类型的对象用作arrayI得到这个错误：致命错误：无法将stdClass类型的对象用作ArrayTanks，现在，与Luis结合使用，它正在工作，谢谢；）谢谢，现在，与Luis结合，它正在发挥作用，谢谢；）