好的，这里有几件事：
-
您不需要顶部的变量分配。这在 C 和其他语言中非常重要，但 PHP 不需要。
-
您的if(isset($_GET['firstName'])) $firstName = $_GET['firstName']; 语句使用$_GET 而您的<form> 标签使用$_POST - 这是您的主要问题
-
我建议使用变量数组，如下所示：
$address_vars = array(
array(
'element_name' => 'firstName',
'title' => 'First Name',
'validation' => 'text',
),
array(
'element_name' => 'lastName',
'title' => 'Last Name',
'validation' => 'text',
),
);
然后您可以像这样以编程方式输出字段：
foreach($address_vars as $cur_address_field) {
?>
<label><?php echo $cur_address_field['title']; ?>: <input type = "text" value="<?php echo (isset($_POST[$cur_address_field['element_name']]) ? $_POST[$cur_address_field['element_name']] : ''); ?>" id = "<?php echo $cur_address_field['element_name']; ?>" placeholder = "<?php echo $cur_address_field['title']; ?>" name ="<?php echo $cur_address_field['element_name']; ?>"></label>
<?php
}
这不仅大大清理了代码，而且还使更改/更新甚至添加到字段变得更加容易（并且更安全）。
然后，要验证字段，您可以使用我设置为开关的validation 数组键来遍历所有字段。像这样的：
foreach($address_vars as $validate_field) {
if($validate_field['validation'] == 'text') {
// this is a text-based field, so we check it against the text-only regex
$string_exp = "/^[A-Za-z .'-]+$/";
if(!preg_match($string_exp, $_POST[$validate_field['element_name']])) {
$message .= '<li>Please enter a ' . strtolower($validate_field['title']) . ' containing letters and spaces only.</li>';
}
} elseif($validate_field['validation'] == 'email') {
$email_exp = '/^[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}$/';
if(!preg_match($email_exp, $_POST[$validate_field['element_name']])) {
$message .= '<li>Please enter a valid ' . strtolower($validate_field['title']) . '.</li>';
}
}
}
-
您没有正确连接您的产品字段。用户提交的值无法在此处“粘贴”，因此该字段的值完全丢失了。首先，我们可以将这些都放在一个数组中，类似于我们对地址字段所做的：
$product_vars = 数组（
大批（
'element_name' => '乐队',
'标题' => '乐队',
'选项' => $bands,
'占位符' => '选择一个',
),
大批（
'元素名称' => '颜色',
'标题' => '颜色',
'选项' => $颜色，
'占位符' => '选择一个',
),
);
那么我们可以使用以下形式：
foreach($product_vars as $cur_product) {
?>
<label><?php echo $cur_product['title']; ?>: </label>
<select name="<?php echo $cur_product['element_name']; ?>" size="1">
<option><?php echo $cur_product['placeholder']; ?></option>
<?php
foreach($cur_product['options'] as $cur_option)
{
echo "<option value = '".$cur_option."' ".(isset($_POST[$cur_product['element_name']]) && $_POST[$cur_product['element_name']] == $cur_option ? "selected='selected'" : "")."> $cur_option </option>";
}
?>
</select>
<?php
}
希望这会有所帮助！
**因共享新代码而编辑**
这里又发生了一些事情。主要项目是：$product_vars foreach 位于 <form> 标记之外，<form> 标记未设置为使用 $_POST，尽管其余代码均以这种方式设置，并且未添加任何验证类型。我已经粘贴了我拥有的完整代码，这对我有用。
<?php
//arrays
$bands = array ("ACDC", "Journey", "Modest Mouse", "Band of Horses", "Vampire Weekend", "Of Monsters and Men", "Broken Bells", "Phoenix", "Fleetwood Mac", "AJR",);
$colors = array ("Black", "Navy", "Red", "Orange", "Pink", "Yellow", "Green", "Gray", "White", "Purple",);
$sizes = array ("X-Small", "Small", "Medium", "Large", "X-Large", "XX-Large", "XXX-Large",);
$styles = array ("Tank Top", "T-Shirt", "Long Sleeve", "Hoodie", "Sweatshirt", "Jacket",);
$product_vars = array(
array( 'element_name' => 'band', 'title' => 'Band', 'options' => $bands, 'placeholder' => 'Choose One', ),
array( 'element_name' => 'color', 'title' => 'Color', 'options' => $colors, 'placeholder' => 'Choose One', ),
array( 'element_name' => 'size', 'title' => 'Size', 'options' => $sizes, 'placeholder' => 'Choose One', ),
array( 'element_name' => 'style', 'title' => 'Style', 'options' => $styles, 'placeholder' => 'Choose One', ),
);
$address_vars = array(
array( 'element_name' => 'firstName', 'title' => 'First Name', 'validation' => 'text',),
array( 'element_name' => 'lastName', 'title' => 'Last Name', 'validation' => 'text',),
array( 'element_name' => 'email', 'title' => 'Email Address', 'validation' => 'email',),
array( 'element_name' => 'phone', 'title' => 'Phone Number', 'validation' => 'phone',),
array( 'element_name' => 'address', 'title' => 'Address', 'validation' => 'address',),
array( 'element_name' => 'city', 'title' => 'City', 'validation' => 'text',),
array( 'element_name' => 'state', 'title' => 'State', 'validation' => 'text',),
array( 'element_name' => 'zip', 'title' => 'Zip Code', 'validation' => 'zip',),
);
?>
<form action="" method="post">
<?php
foreach($product_vars as $cur_product) {
?>
<label><?php echo $cur_product['title']; ?>: </label>
<select name="<?php echo $cur_product['element_name']; ?>" size="1">
<option><?php echo $cur_product['placeholder']; ?></option>
<?php
foreach($cur_product['options'] as $cur_option)
{
echo "<option value = '".$cur_option."' ".(isset($_POST[$cur_product['element_name']]) && $_POST[$cur_product['element_name']] == $cur_option ? "selected='selected'" : "")."> $cur_option </option>";
}
?>
</select>
<?php
}
foreach($address_vars as $cur_address_field) {
?>
<label><?php echo $cur_address_field['title']; ?>:
<input
type = "text"
value="<?php echo (isset($_POST[$cur_address_field['element_name']]) ? $_POST[$cur_address_field['element_name']] : ''); ?>"
id = "<?php echo $cur_address_field['element_name']; ?>"
placeholder = "<?php echo $cur_address_field['title']; ?>"
name ="<?php echo $cur_address_field['element_name']; ?>">
</label>
<?php } ?>
<input type="reset" class="buttons">
<input type="submit" class="buttons">
</form>
<?php
foreach($address_vars as $validate_field) {
$message = validate_field_contents($_POST[$validate_field['element_name']], $validate_field['title'], $validate_field['validation'], $message);
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<title>T-Shirt Form</title>
<link type="text/css" rel="stylesheet" href="css/style-prod.css">
<script src="..js/script.js" defer></script>
</head>
<body>
<?php
if($message) {
echo '<p>'.$message.'</p>';
} else {
?>
<!--display processed information here-->
<h3 class="subheaderone">Thank you for your order!</h3><br>
<h3 class = "subheadertwo">Product:</h3>
<div class = "output">
<h3 class = "subheadertwo">Shipping & Contact Information:</h3>
<?php foreach($address_vars as $cur_address) {
echo '<p>' . $cur_address['title'] . ': ' . (isset($_POST[$cur_address['element_name']]) ? $_POST[$cur_address['element_name']] : '') . '</p>';
} ?>
</div>
<div class="another">
<nav><a href="./products.php"> Submit Another Form</a></nav>
</div>
<?php } ?>
</body>
</html>
<?php
function validate_field_contents($content, $title, $type, $message) {
if($type == 'text') {
// this is a text-based field, so we check it against the text-only regex
$string_exp = "/^[A-Za-z .'-]+$/";
if(!preg_match($string_exp, $content)) {
$message .= '<li>Please enter a valid ' . strtolower($title) . ' containing letters and spaces only.</li>';
}
} elseif($type == 'email') {
$email_exp = '/^[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}$/';
if(!preg_match($email_exp, $content)) {
$message .= '<li>Please enter a valid ' . strtolower($title) . '.</li>';
}
}
return $message;
}