PHP提交文本带有 and 数字 服务器提示出错

 <form action="test.php" method="post">
<input class="inputtext" name="str1" type="text" value="test and 1 test">
<input type="submit" value="提交">
</form>
<?php
  $a=$_POST['str1']; 
  echo $a;
?>

例如输入test and 1 test这串提交的话会出错, test and s test 这样正常
带有and 加数字就会报错.
POST 和GET都一样
出错信息

Forbidden

You don't have permission to access /test.php on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

查看一下php内置函数 ctype_alpha()这个是验证输入内容是否是纯字母的函数！