很遗憾，您需要对其进行评估.

Unfortunately, you need to eval it.

如果值是这样的:

$deviceData["devicename"] = [
    'a' => 20,
    'b' => 30,
    'c' => 580
];

您可能想要隔离它们，因为如果有超过 3 个等，您需要 extract() 来使用它们，封装在函数/闭包中会起作用.

You might want to isolate them as you will need to extract() them out to make use if there is more then 3 etc, encapsulating in function/closure would work.

<?php
$formula = '(($a+$b)/$c)';

$deviceData["devicename"] = ['a' => 20, 'b' => 30, 'c' => 580];

$runFormula = function ($formula, $data) { 
    extract($data); 
    return eval('return '.$formula.';'); 
};

echo $runFormula($formula, $deviceData["devicename"]);

https://3v4l.org/I2rbk

或者只是:

extract($deviceData["devicename"]); 
echo eval('return '.$formula.';'); 

但是您正在使用提取的内容污染全局变量表，可能会导致更多问题.

But you're polluting your global variable table with whats extracted, potentially causing more issues.

虽然如果公式是由用户定义的，请不要使用 eval，否则您会遇到安全问题.

Though dont use eval if the formula is defined by the user, or your will have security issues.

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