用户输入字符串通过url传递

I am building a travel website where people can build up their travel itineraries.

There are pre built itineraries with cities and the users can click a button "Add to Itinerary" and this adds to the databse - this work fine.

I also want the opportunity for the user to add their own cities. The way I want to do this is by them clicking a button similar to "Add to Itinerary" but then they enter the name of this city and add to the list that way.

This is the code I have for the "Add to Itinerary" which is working.

<?php
if ( $_SESSION['user'] != "" ) {
  if ( in_array("Bangkok", $aray) ) { ?>
    <button class="buttonAddedItinerary">Already Added </button>
  <?php
  } else {
    ?>
    <a href="process.php?action=addtoItinirary&UCty=Bangkok">
      <button class="buttonAddItinerary">Add to Itinerary</button>
    </a>
  <?php
  }
}
?>

So basically I want when I click the button:
<a href="process.php?action=addtoItinirary&UCty=USERINPUT"...

This is basic HTML form creation and processing. Any beginners PHP tutorial from the last 10+ years will show you how to do this. You will use method="GET" in your form tag.

Here's the tutorial from the PHP docs: http://us1.php.net/manual/en/tutorial.forms.php

You could use GET to pass user input and add it to the URL. So when when user input is present replace process.php?action=addtoItinirary&UCty=Bangkok with process.php?action=addtoItinirary&UCty=UserCity

Just sanitize the user input afterwards.