PHP数组未定义索引

Question

我搜索了谷歌和堆栈溢出论坛，他们反复说使用isset()来确保索引被定义，但是很少有人给我一个想法，如果索引没有设置该怎么办。

下面是我的简单代码:

<?php
    $allStaff = $this->registry->getData('staff');
    $departments = array();
    foreach($allStaff as $staff){
        if(isset($departments[$staff['department']])){
            $departments[$staff['department']][count($departments[$staff['department']])] = $staff;
        }
        else {
            $departments[$staff['department']][count($departments[$staff['department']])] = $staff;
        }

标识系统的一个例子是:$departments['Management'][0]['name/staff position/etc']

我试过把$departments[$staff['department']] = 0，因为我看了其他用户的一些答案，但它不起作用，给了我更多的错误。请帮忙，谢谢

Answer 1

这会给你带来问题:

count($departments[$staff['department']])

所以你要确保它有一些兼容的东西分配给它，然后你可以使用它:

if (!isset($departments[$staff['department']]))
    $departments[$staff['department']] = array();
$departments[$staff['department']][count($departments[$staff['department']])] = $staff;

PHP默认将为您处理顺序数字索引，因此您可以将上面的代码简化为(感谢BNC提供的灵感):

if (!isset($departments[$staff['department']]))
    $departments[$staff['department']] = array();
$departments[$staff['department']][] = $staff;

请注意，你的代码有一个模式，如P[Q[i]][j] = Q，将工作正常，只是不经常看到。

Answer 2

不清楚您在这里要做什么。我猜你是想数一下每个部门有多少员工。如果我猜错了，请用英语陈述你的目标(不是代码)。如果我猜对了，…

$allStaff = $this->registry->getData('staff');
$departments = array();
foreach($allStaff as $staff){
    if( !isset($departments[$staff['department']]) ) {
        $departments[$staff['department']] = 0;
    }
    $departments[$staff['department']] += 1;
}

更新:等等，我想我刚刚弄清楚了(当[]足以追加到数组时，我被count()的使用误导了)。我猜你想让员工按部门分组，…

$allStaff = $this->registry->getData('staff');
$departments = array();
foreach($allStaff as $staff){
    if( !isset($departments[$staff['department']]) ) {
        $departments[$staff['department']] = array();
    }
    $departments[$staff['department']][] = $staff;
}