header in php for redirecting - php

Question

New code
$count= mysqli_num_rows($result);
if ($count==1){
$row=mysqli_fetch_row($result);
if(($row[1]==$username) && ($row[2]==$password))
{
echo $row[1];
$_SESSION["myusername"]= $username;
$_SESSION["mypassword"]= $password;
header("location: login_success.php");
exit();
} else {
echo "No user found";
}
} else {
echo "No rows selected";
//}
mysqli_close($dbc); // Closing Connection
}
}
?>
I modified the code but the header statement is causing it to stop. If I delete the header it works as expected.

Answer 1

$username = stripslashes($sent_username); is the culprit since you are saving the fetched username in $sent_user and not $sent_username. Since that is what you're using in your query:
$sql="SELECT * FROM $tbl_name WHERE username='$username' and password='$password'";
Where $username does not make any sense if you roll back and see what it really holds i.e. $username = stripslashes($sent_username);, Now you see the culprit $sent_username, Where is it? No where, a typo indeed.
Instead of this:
$sent_user=$_POST['myusername'];
$sent_password=$_POST['mypassword'];
$username = stripslashes($sent_username);
$password = stripslashes($sent_password);
Try this:
$sent_user=$_POST['myusername'];
$sent_password=$_POST['mypassword'];
$username = stripslashes($sent_user);
$password = stripslashes($sent_password);
EDIT:
This should solve your problem, however there are a couple things you should re-check.
1) Proper syntax for header:
Instead of this:
header("location:login_success.php");
use this:
header("Location: login_success.php");
2) echo your query to see what really is happening, correct table with proper column and the proper values are being sent.
3) How could I forget the most important part, No matter what you do regarding sessions, ALWAYS write session_start(); in the beginning of your code in every file you intend to use sessions in.
^An Example:
<?php
session_start();
$host="localhost"; // Host name
$db_username=""; // Mysql username
$db_password=""; // Mysql password
$db_name="test_db_connection"; // Database name
$tbl_name="logintable"; // Table name
$error=''; // Variable To Store Error Message
if (isset($_POST['submit']))
//

Answer 2

Remove the:
echo $row[1];
Above the header command. Headers must always happen before any other output is provided to the client. This is because in the HTTP spec, headers come first and must be in the right format.
If you attempt to use Header in PHP after you have sent other content to the client then it will trigger a warning because you have tried to violate the HTTP specification. This is what the documentation says:
Remember that header() must be called before any actual output is sent, either by normal HTML tags, blank lines in a file, or from PHP. It is a very common error to read code with include, or require, functions, or another file access function, and have spaces or empty lines that are output before header() is called. The same problem exists when using a single PHP/HTML file.
http://php.net/manual/en/function.header.php