PHP nl2br（）基本功能(PHP nl2br() basic function)

 有人可以帮我这个邮件脚本。 
 
 我只是想发送一封html电子邮件，部分消息来自用户textarea，它放在\ r \ n中。 
 
 我似乎无法使用nl2br或任何其他类似的功能。 下面的代码不是我正在使用但仍然产生错误。 
 
 代码： 
 
$to  = 'example@gmail.com';

$subject = 'Test Subject';

$message_var_1 = 'test1 \r\n test2 \r\n test3';
$message = nl2br("
    <div>
    <div>$message_var_1</div>
    </div>
");

$headers  = 'MIME-Version: 1.0' . "\r\n";
$headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
$headers .= 'X-Mailer: PHP/'.phpversion() . "\r\n";

mail($to, $subject, $message, $headers);

Can somebody please help me with this mail script. 
 
I'm simply trying to send an html email and part of the message is from a user textarea, which puts in \r\n.
 
I seem to be unable to use nl2br or any other similar function. The code below isn't what I'm using but still produces the error.
 
The code:
 
$to  = 'example@gmail.com';

$subject = 'Test Subject';

$message_var_1 = 'test1 \r\n test2 \r\n test3';
$message = nl2br("
    <div>
    <div>$message_var_1</div>
    </div>
");

$headers  = 'MIME-Version: 1.0' . "\r\n";
$headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
$headers .= 'X-Mailer: PHP/'.phpversion() . "\r\n";

mail($to, $subject, $message, $headers);

原文：https://stackoverflow.com/questions/3396147