Pass value of html to PHP variable - php

Question

I'm having some trouble passing the value of some HTML elements to PHP variable. I have a PHP web app where I give the users some drop down option. What I want to do is after the user has selected the option I give than to click on a button and make some calculations based on his/her selection.
I have tried using the POST and GET method but because I'm new to php I probably did it wrong. I also try with ids but no results.
Here is the HTML code
The 1st dropdown menu :
<div>
<select id="kleidwma" onchange="kleidwmata_change(this.value);kwdikos();ypsos();"
class="form-control selectpicker kleidwmata" data-size="10" data-
style="btn-white" name="guard_kleidwmata" required >
<option value="" > </option>
<option value="12">12 MS</option>
<option value="14">14 KETE</option>
<option value="15">15 ARRIKTON</option>
<option value="16">16 KETE</option>
<option value="22">22 KETE</option>
</select>
</div>
The 2nd dropdown menu :
<div>
<select id="sigkratisi" onchange="kwdikos()" name="sigkratisi"
class="form-control sigkratisi" required>
<option value="" ></option>
<option value="metalliki" >Μεταλλική</option>
<option value="xilogonia" >Ξυλογωνία</option>
</select>
</div>
Here is the button to be clicked after the selection has been made :
<div class="row" style="margin-top:20px; margin-left: 235px;">
<div class="col-md-7">
<input type="hidden" name="tmp_calculate" value="pending" />
<button onclick="calculate()" type="button" class="btn btn-success" >
<?php echo "Υπολογισμός";?></button>
</div>
</div>
And finally here is the function that is called :
function calculate()
{
$var1 = sigkratisi;
$var2 = kleidwma;
"code to be executed base on the var1 and var2"
}
I hope it's clear enough.
Thanks in advance for your time

Answer 1

you can use Forms
<form name="f" action="" method="POST">
<div>
<select id="kleidwma" name="variable"
class="form-control selectpicker kleidwmata" data-size="10" data-
style="btn-white" name="guard_kleidwmata" required >
<option value="" > </option>
<option value="12">12 MS</option>
<option value="14">14 KETE</option>
<option value="15">15 ARRIKTON</option>
<option value="16">16 KETE</option>
<option value="22">22 KETE</option>
</select>
<input type="submit" value="submit" />
</div>
</form>
in PHP
<?php
if(isset($_POST['variable']))
{
echo $_POST['variable'];
}
?>