带有preg_match的php字母数字模式

谁能给我解释一下为什么这个模式被识别为字母数字?

' 13 ' ' 13 ' 13 ' ' ' 13 ' ' 13234234 ' 3

请查看此链接的图像在这里输入链接描述

我编写代码只是为了向您展示它可以被识别为字母数字

EDIT 15.06.214 21:40

我补充了一些信息，对不起，我忘了。

您看到的变量取自一个输入表单。这是我使用的代码，以便使信息干净，并准备插入到数据库中。

PS:仅供您参考，变量$errform稍后用于"触发"页面上的错误消息

    <?php
  $username = $password = $fname = $lname = $mail = $id_dept = "";
  $usernameERR = $passwordERR = $fnameERR = $lnameERR = $id_deptERR = "";
  $errform = 2;
?>
<?php
  if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $username = clean_data($_POST["username"]);
    $password = clean_data($_POST["password"]);
    $fname = clean_data($_POST["fname"]);
    $lname = clean_data($_POST["lname"]);
    $mail = clean_data($_POST["mail"]);
    $id_dept = clean_data($_POST["id_dept"]);
    if (!preg_match("/^[a-zA-Z0-9]*$/", $username)) {
        $usernameERR = "Only letters and numbers allowed";
      }
    if (!preg_match("/^[a-zA-Z0-9]*$/", $password)) {
        $passwordERR = "Only letters and numbers allowed";
      }
    if (!preg_match("/^[a-zA-Z ]*$/", $fname)) {
        $fnameERR = "Only letters and white space allowed";
      }
    if (!preg_match("/^[a-zA-Z ]*$/", $lname)) {
        $lnameERR = "Only letters and white space allowed";
      }
  }
  function clean_data($data) {
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    return $data;
  }
  if (isset($_POST['submit'])) {
    if ((!preg_match("/^[a-zA-Z0-9]*$/", $username))
    || (!preg_match("/^[a-zA-Z0-9]*$/", $password))
    || (!preg_match("/^[a-zA-Z ]*$/", $fname))
    || (!preg_match("/^[a-zA-Z ]*$/", $lname))) {
      $errform = 1;
    } else {
      $errform = 0;
      $con = mysqli_connect($hostdb,$userdb,$passwdb,$dbTEST);
      if (mysqli_connect_errno()) {
        echo "Impossibile connettersi a MySQL: " . mysqli_connect_error();
      }
      $username = mysqli_real_escape_string($con, $_POST['username']);
      $password = md5(mysqli_real_escape_string($con, $_POST['password']));
      $fname = mysqli_real_escape_string($con, $_POST['fname']);
      $lname = mysqli_real_escape_string($con, $_POST['lname']);
      $mail = mysqli_real_escape_string($con, $_POST['mail']);
      $id_dept = mysqli_real_escape_string($con, $_POST['id_dept']);
      if (!mysqli_query($con, "INSERT INTO user (id_user, username, password, fname, lname, mail, id_dept) VALUES (NULL, '$username', '$password', '$fname', '$lname', '$mail', '$id_dept')")) {
        die ("Error: " . mysqli_error($con));
      }
      mysqli_close($con);
    }
  }
?>

编辑15/06/2014 22:41

,

对不起，我明白问题的根源了。

我检查的是

(preg_match("/^[a-zA-Z0-9]*$/", $username))

在我的代码中，$username得到了这种处理

    $username = clean_data($_POST["username"]);
    if (!preg_match("/^[a-zA-Z0-9]*$/", $username)) {
        $usernameERR = "Only letters and numbers allowed";
      }

,

    function clean_data($data) {
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    return $data;
  }

所以当我发布' ' ' q ' ' ' q ' ' ' q这是剥离和成为qqqqqqqqq

但是，有两个问题。第一个问题是我回显了

echo "post username: " . $_POST["username"];

与

比较

echo "preg username " . preg_match("/^[a-zA-Z0-9]*$/", $username);

，很明显$_POST["username"]不是==到$username，因为最后一个得到了clead_data函数的处理，而POST没有。

当我做preg_match的时候，我做的是$username = qqqqqqqqqqq(这是一个字母数字)而我给你看的是$_POST['username'] = 'q'q'q'q'q'q'q'q'q'q'q 'q'q'q'q

第二个问题是我向数据库发送了这个

$username = mysqli_real_escape_string($con, $_POST['username']);

而我应该发送这个

$username = mysqli_real_escape_string($con, $username);

所以在数据库上到达了NON - CLEANED数据