php - php页面出现未定义索引的警告，如何去除？

Question

php 页面正在工作，但在界面上发出警告，我想删除这些警告。警告是 undefined index ，如下所示。

“注意:未定义索引:在第 31 行 C:\wamp\www\booking.worldtravelguide.net\registera.php 中注册”

<form method="POST" name="register" id="register" action="?register=true"><p>
<p>
<h1>Sign up</h1>
<p><label>First Name</label> <input type="text" name="fname" size="20"><p>
<p><label>Last Name</label> <input type="text" name="lname" size="20"><p>
<p><label>Email&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </label> <input type="text" name="email" size="20"><p>
<p><label>Password&nbsp;&nbsp;</label> <input type="password" name="password" size="20"><p>
<p><input type="submit" value="Submit" name="submit">
</form>
<?php
$host="localhost";
$uname="root";
$pass="";
$database = "homedb";

$connection=mysql_connect($host,$uname,$pass) or 
die("Database Connection Failed");

$selectdb=mysql_select_db($database) or 
die("Database could not be selected");  

$result=mysql_select_db($database) or 
die("database cannot be selected");

@session_start();
set_time_limit(0);




if($_GET['register']=='true')
{

$fname = mysql_real_escape_string($_POST['fname']);
$lname = mysql_real_escape_string($_POST['lname']);
$email = mysql_real_escape_string($_POST['email']);
$password = mysql_real_escape_string(md5($_POST['password']));
$status = 'inactive';

mysql_query("insert into `regitera` set fname = '".$fname."',
lname = '".$lname."',
email = '".$email."',
password = '".$password."',
status = '".$status."'");
$iduser = mysql_insert_id();

/* You can write your activation mail program here */
/* Or You can redirect user to My account Page */
$str="Welcome to A2Z webhelp";
header("Location:index.php?msg=$str");
}


?>

Answer 1

if(isset($_GET['register']) && $_GET['register']=="true") ...