about php error called Parse error: syntax error, unexpected '&&' (T_BOOLEAN_AND), ex

[mareye]

<?php
session_start();  //register the session.
if(isset($_POST['username']&&$_POSt['password']))  //if whethere the username and password is not set.
{
$username=$_POST['username'];      //assign $username variable to the sent username.
$password=md5($_POST['password']); //make encycrpit the password.
$conn=mysql_connec("localhost","root") or die(mysql_error()); //make connection.
$mysql_select_db("system",$conn) or die(mysql_error()); // select the database.
$sql="select * from instructor where username='$username' and password='$password'";//write the query.
$result=mysql_query($sql,$conn);     //run the query.
if(mysql_num_rows($result)==1)      // check that the number of row is 1 or not if 1 it is correct.
{
echo"you are successfully login as".$username;
//<a href="http://bytes.com/logoutpage.php">logout</a><br>  //create a link.
//<a href="http://bytes.com/registrationform.php">register<a>  //create alink.
}
else
{
echo"wrong password or username please try again";
header("location:main.php"); //redirect to the main.php.
}
}
else
{
echo"you must enter the required information";
}
 
 ?>

this is the code but it displays an error on line 3 the error is called Parse error: syntax error, unexpected '&&' (T_BOOLEAN_AND), expecting ',' or ')' in C:\wamp\www\try1\open.php on line 3

[anonuser]

if(isset($_POST['username']&&$_POSt['password']))

should read

if ((isset($_POST['username']) && (isset($_POST['password']))

i hope you're sanitizing your input - using POSTs directly like this invite problems :-)

[Dormilich]

note: isset() allows to check multiple variables at once.

if (isset($_POST['username'], $_POST['password']))