PHP-从数组获取值 [英] PHP - Get values from Array

问题描述

我正在尝试从数组中检索值。下面是代码：

I am trying to retrieve a value from an Array. Here is the code:

$opt=get_records_sql($sql1);

print_object($opt);

$n = count($opt);
if (empty($opt)){
    echo 'No options selected';
}
else{
    $optno = $opt["subjectid"];
    echo '<br>$optno = '.$optno;
}

我尝试使用： $ opt [ subjectid ] ，但出现以下错误：

I tried to use: $opt["subjectid"] but I get the following error:

Notice: Undefined index: subjectid

数组内容：

Array
(
    [1] => stdClass Object
        (
            [uname] => JHollands06
            [tutor] => M LSt
            [subjectid] => 1
            [year] => 2010
            [optid] => 1
        )

)

如何获取值为1的数据主题？

How to I fetch the data subjectid which has value 1?

推荐答案

方法1：通过强制转换将对象转换为数组。

Method 1: Convert the object to an array by casting it.

$opt[1] = (array) $opt[1];
echo $opt[1]['subjectid'];

要转换数组中的所有对象（如果有多个）：

To convert all objects in an array (if there are more than one):

foreach ($opt as $k => $val) {
    $opt[$k] = (array) $val;
}

方法2：只需将其称为对象

echo $opt[1]->subjectid

数组和对象之间是有区别的。对象包含必须使用->调用的变量，而数组包含与特定键相关联的值。作为输出状态，您有一个包含stdClass对象的数组，而不是另一个数组。

There is a difference between an array and an object. An object contains variables that have to be called using the '->' and an array contains values which are associated with a specific key. As your output states, you have an array containing an stdClass object, not another array.

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