我正在尝试编写一个程序来读取一个文件，并将从标准输入中读取的字符的每个外观加倍。
printf("$\n"); r+检查必须加倍的字符是否达到文件中出现的次数，这是正确的。但是运行程序后文件的内容保持不变。
我理解w+和<form method="post" name="contact_form" action="Contact.php">
Your Name: <input type="text" required name="name">
Email Address: <input type="text" required name="email">
Message: <textarea required name="message"></textarea>
<input type="submit" value="Submit">
</form>
<?php
$errors = '';
$myemail = 'enterDesiredEmail';
if(empty($_POST['name']) || empty($_POST['email']) || empty($_POST['message'])) {
$errors .= "\n Error: all fields are required";
}
$name = null;
$email_address = null;
$message = null;
$name = $_POST["name"];
$email_address = $_POST["email"];
$message = $_POST["message"];
if (!preg_match("/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/i",$email_address)) {
$errors .= "\n Error: Invalid email address";
}
if( empty($errors)) {
$to = $myemail;
$email_subject = "Contact form submission: $name";
$email_body = "You have received a new message. ".
" Here are the details:\n Name: $name \n ".
"Email: $email_address\n Message \n $message";
$headers = "From: $myemail\n";
$headers .= "Reply-To: $email_address";
mail($to,$email_subject,$email_body,$headers);
}
?>
之间的区别;我不明白的是为什么这个程序不会加倍从输入读取的每个'x'字符。
我做错了什么？