PHP检查它是否包含字母数字或空格以外的任何内容

我有一个发送字符串的表单。就这么简单：

<form action="test2.php" method="POST">
String: <input type="text" name="string" />
<br /><input type="submit" value="Send >" />
</form>

字符串：

下面是test2.php：

<?php
$string = $_POST['string'];
preg_replace("/[^0-9a-zA-Z ]/", "", $string {
echo "You can't have any symbols in your username.";
} else {
echo "Nice string!";
}
?>

---

您的语法完全无效。你想要这样的东西：

<?php
$string = $_POST['string'];
if ( preg_match("/[^0-9a-zA-Z ]/", $string) ) {
    echo "You can't have any symbols in your username.";
} else {
    echo "Nice string!";
}
?>

我发现了一个致命错误。将其标记为已接受，然后单击复选标记。