php post form to another php

Create a text field by the name of val inside the form on index file eg:

<form action="search.php" method="post">
  <input type="text" name="val" value="search string" />
  <!-- more form stuff -->
</form>

And you can now get it like:

<?php echo $_POST['val']?>

If however, you want that value in url you should modify the form's method to get like:

<form action="search.php" method="get">
  <input type="text" name="val" value="search string" />
  <!-- more form stuff -->
</form>

and then you can get its value on search page like:

<?php echo $_GET['val']?>

Alternatively, you can specify search string directly in the action attribute of the form and in this case you don't need the val field:

<form action="search.php?val=<?php echo $search_string;?>" method="get">
  <!-- more form stuff -->
</form>

and then you can get its value on search page like:

<?php echo $_GET['val']?>

What you are looking to achieve can be described as URL parameter passing or query string. The idea is that you can pass values through the URL, denoted by ?variable=value. Important parts of URL parameter passing is retrieving the value by using $_GET.

Therefore, change this line of code,

<form action="search.php?val=" method="post">

to this line of code,

<form action="search.php" method="get">

You do not need to add the action to include, ?val, PHP will do that for you as long as you have an input field with the name attribute as val.

<form action="search.php" method="get">
<input type="text" name="val"/>
<input type="submit" />
</form>

Once submitted you should have the URL which looks like,

http://www.example.com/search.php?val=your_text_here

Which from inside search.php you can access your query string using, $_GET superglobal.

<?php
echo $_GET['val'];
?>

You can use both. If you have <form action="search.php?val=...">, then you can access it just as $_GET["val"]. Any other form elements will however show up in $_POST[] for your example.

Btw, in cases where the parameter might be submitted by different forms, use $_REQUEST. It captures both GET and POST content.