给定一个数组$arr = [23,3,45,6,78,8,34],筛选其偶数成员组成新的数组返回，请封装函数 + 简单计算器功能

给定一个数组$arr = [23,3,45,6,78,8,34],筛选其偶数成员组成新的数组返回，请封装函数

<?php
// 给定一个数组
$arr = [23,3,45,6,78,8,34];
// 封装函数
function grouping(array $arr): array {
    // 先声明一个新数组 
    $newArr = [];
    for($i = 0; $i < count($arr); $i++) {
        if($arr[$i] % 2 == 0){
            $newArr[] = $arr[$i];
        }
    }
    return $newArr;
}
$return = grouping($arr);
var_dump($return);
?>

返回的结果

尝试实现简单的计算器功能，语言不限制。

<?php
    error_reporting(E_ALL & ~E_NOTICE);
    if($_POST['button']):
        if($_POST["choice"] == "/" && $_POST["num2"] == 0 || $_POST["choice"] == "%" && $_POST["num2"] == 0):
            echo "除数不能为0";
        endif;
    endif;
?>
    <h2>加减乘除计算器</h2>
    <form action="" method="POST">
        <input type="number" name="num1" id="num1" required value="<?=$_POST['num1']?>"> 
        <select name="choice" id="choice">
            <option value="">--请选择--</option>
            <option value="+" <?=$_POST["choice"] == "+" ? "selected" : "" ?>>+</option>
            <option value="-" <?=$_POST["choice"] == "-" ? "selected" : "" ?>>-</option>
            <option value="*" <?=$_POST["choice"] == "*" ? "selected" : "" ?>>*</option>
            <option value="/" <?=$_POST["choice"] == "/" ? "selected" : "" ?>>/</option>
            <option value="%" <?=$_POST["choice"] == "%" ? "selected" : "" ?>>%</option>
        </select>
        <input type="number" name="num2" id="num2" required value="<?=$_POST['num2']?>">
        <input type="submit" value="等于" name="button">
    </form>
    <?php
    if(isset($_POST['button'])):
        switch($_POST['choice']){
            case "+":
                $sum = (int)$_POST['num1'] + (int)$_POST['num2'];break;
            case "-":
                $sum = (int)$_POST['num1'] - (int)$_POST['num2'];break;
            case "*":
                $sum = (int)$_POST['num1'] * (int)$_POST['num2'];break;
            case "/":
                $sum = (int)$_POST['num1'] / (int)$_POST['num2'];break;
            case "%":
                $sum = (int)$_POST['num1'] % (int)$_POST['num2'];break;
        }
        echo "<span style='color:green;'>{$sum}</span>";
    endif;
?>