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php - 编辑：在 PHP 中计算变量

问题描述

我是 PHP 的初学者，我被分配了创建 Gas Budget 计算器的任务。
我被困在如何添加数学运算并在提交后返回值。这是我在表单中的内容和链接的 PHP 文件之一。

当我按原样运行时，数据会存储在服务器上，但总数不会返回。感觉好像我已经很接近了，但我已经盯着这段代码看了 4 个小时，我的大脑很痛。请帮忙！

先感谢您！

HTML：

    <?php
require_once 'functions.php';
$model = getViewModel();

?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Gas Budget Calculator</title>
<link rel="stylesheet" href="main.css">
</head>
<body>
<main>
<?php if($model->msg): ?>
<p class="error"><?=$model->msg?></p>
<?php endif; ?>
<form action="" method = "post">
    <fieldset>
        <legend>Gas Budget Calculator</legend>
        <div class = "input-field">
            <label for= "type" >Price of Gas:</label>
            <select name = "type">
                <option></option> 
               <?php foreach ($model->price as $value => $label): ?>
                <option value="<?=$value?>"><?=$label?></option>
               <? endforeach; ?>
            </select>
        </div>          

        <div class = "input-field">
            <label for = "commute"> Average Commute Mileage:</label>
            <input type="text" name = "commute" id = "commute">
        </div>

        <div class = "input-field">
            <label for = "mpg"> Car Average Miles Per Gallon (MPG):    </label>
            <input type="text" name = "mpg" id = "mpg">
        </div>
        <div class="input-field">
            <label>
                <input type="checkbox" name="perks">Are you going to use fuel perks? (Check box if yes)
            </label>
        </div>
        <div class = "input-field">
            <label for = "groceries"> If yes, what is the average amount spent on groceries?</label>
            <input type="text" name = "groceries" id = "groceries">
        </div>
        <div class="input-field">
            <button type="submit">Submit</button>
        </div>   
        
        
    </fieldset>
</form>
<?php if ($model->info): ?>
<table>
    <tr>
        <td>Price of Gas </td><td><?=$model->info->type?></td>
    </tr>
    <tr>
        <td>Commute</td><td><?=$model->info->commute?></td>
    </tr>
    <tr>
        <td>Miles Per Gallon</td><td><?=$model->info->mpg?></td>
    </tr>
    <tr>
        <td>Fuel Perks?</td><td><?=$model->info->perksYesNo()?></td>
    </tr>
    <tr>
        <td>Average Groceries</td><td><?=$model->info->groceryAverage()?></td>
    </tr>
    <tr>
        <td>Total</td><td><?=$model->info->calculateTotal()?></td>
    </tr>
    
</table>
<?php endif; ?>

    </body>
</html>

PHP：

class viewModel {
public $info;
public $msg;

public $price = [
            '87 octane' => 1.89, 
            '89 octane' => 1.99, 
            '92 octane' => 2.09
        ]; 

    if(isset( $_POST['Submit']) {
            if($msg!='')
        
}
    class GasInfo {
    private $isPerks;

    public $type;
    public $commute;
    public $mpg;
    public $groceries;
    public $total;

    public function __construct(int $type, int $commute, int $mpg, bool $perks, int $groceries,       int $total){
        $this ->type = $type;
        $this ->commute = $commute;
        $this ->mpg = $mpg;
        $this ->perks = $perks;
        $this ->groceries = $groceries;
        $this ->total = $total;
    }
public function isValid(): bool {
if (empty($this->commute)) {
    return false;
}

if (empty($this->mpg)) {
    return false;
}

return true;
}
    function perksYesNo(): string {
        return $this->isPerks ? 'Yes' : 'No';
    }

    function groceryAverage(int $groceries){
        return floor( $groceries/100);
    }


function calculateTotal (int $type, int $commute, int $mpg, bool $perks, int $groceries, int $total){
if ($perks == 'on'){
    $total = ($commute / $mpg)*$type;
} else {
    $total = ($commute / $mpg) * ($type - $groceries);
}
return $total;
echo "You spend $" + $total + " on gas every day.";
}
}

更多PHP：

<?php

require_once 'GasInfo.php';


function getViewModel(): ViewModel {
$model = new ViewModel();

 }  
return $model;
}   



function handleSubmit() {
    if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
        return null;
    }
   
   
    $type = $_POST['type'];
    $commute = $_POST['commute'];
    $mpg = $_POST['mpg'];
    $isPerks = isset($_POST['perks']) ?? null;
    $groceries = $_POST ['groceries'];
    $total = $_POST('total');


    $info = new GasInfo(
        (int)$type,
        (int)$commute,
        (int)$mpg,
        $isPerks,
        (int)$groceries,
        (int)$total
    );
    if (!$info->isValid()) {
        throw new Exception("Please enter gas price, commute, and miles per gallon");
    }

    return $info;

}

标签： phpformsvariablescalculation

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