计算 php 中的两个或多个变量

Question

我有以下 JSON:

 [{
  "units": "06-019",
  "duration_1": "4.96",
  "custom0": "",
  "absolute_mileage_end_0": "31694 km",
  "duration_0": "18.02",
  "duration_stay_0": "7.33",
  "mileage_0": "261 km"
},
{
  "units": "06-021",
  "duration_1": "6.26",
  "custom0": "",
  "absolute_mileage_end_0": "91380 km",
  "duration_0": "21.10",
  "duration_stay_0": "7.66",
  "mileage_0": "603 km"
},
{
  "units": "06-287",
  "duration_1": "10.61",
  "custom0": "",
  "absolute_mileage_end_0": "119741 km",
  "duration_0": "26.67",
  "duration_stay_0": "11.53",
  "mileage_0": "541 km"
},
{
  "units": "06-289",
  "duration_1": "2.44",
  "custom0": "",
  "absolute_mileage_end_0": "89425 km",
  **"duration_0": "7.78",**
  "duration_stay_0": "2.98",
  "mileage_0": "169 km"
}]

我将捕获以下公式

$formula= "duration_0-duration_1";

如何使用 eval() 函数根据 PHP 中数组中每个元素的公式计算结果？

Answer 1

解码JSON并循环播放。然后在公式中，使用 strtr 和 eval 将数组键替换为值：

$formula = "duration_0-duration_1";
$array   = json_decode($json, true);

foreach($array as $values) {
    $calc = strtr($formula, $values);
    eval("echo $calc . PHP_EOL;");
    // or
    eval("$result = $calc;");
}

计算 php 中的两个或多个变量

Compute two or more variables in php

php

eval

formula