post more value in href tag

I want to pass my dropdown value to the controller .

when i click this add button only one value can pass.


<a href="'.site_url("").'User/addsubjects/'.$row['subcode'].'" class="btn btn-info">Add</a> </td>';


can i able to pass two values (dropdown ,subcode) values to the controller

Drop-down is browser side, so while technically you can add more attributes to URL, and your Controller can pick these up, you would either had to build a JS script that appends to href value, or you would have to change A tag to a Form submission:

Code:

<from action="<?= site_url("").'User/addsubjects/'.$row['subcode'] ?>" method="POST">
<select name="dropdown">...</select>
<input type="text" name="subcode">
<button>Add</button>

PHP Code:

// Controller
public function addsubject()
{
    $dropdown = $this->input->post('dropdown');
    $subcode = $this->input->post('subcode');
} 


Also, a quick note, to make code more readable, you should add all URL attributes inside site_url function like this

PHP Code:

site_url('User/addsubjects/'.$row['subcode']); 


Both ways technically work, but this is tidier and intended way.