Drop down Menu PHP

[tridentmist]

I'm trying to code a drop-down menu that has four options; one for pie,exp, root 3, and the golden ratio.(all math values)  Beside the drop-down menu, there is an option for user-inputted data, they must input only positive numbers. I must take there selected drop-down menu option and times it by the user inputted number. I'm not sure how to check which option the user chose.

    <form id="s" method="post">
      <select id="math" name="options">
        <option value="nothing">Please select a constant</option>
        <option value="pie">Pi</option>
    <option value="econs">e</option>
    <option value="ratio">Golden Ratio</option>
    <option value="root">Root 3</option>
  

      </select>

    <input type="submit" name="Submit" value="Send">

Everything That ive tried has failed

[ginerjm]

Where is the input value for the user's number?

And where is the php code that is processing your html ?

[tridentmist]

1 minute ago, ginerjm said:

Where is the input value for the user's number?

And where is the php code that is processing your html ?

Honestly, I'm very new to this.  this is the most recent code i've created. still doesn't work 

 

<?php $choice = $_GET['choice']; ?>

<form id="s" method="post">

  <label for="first">Constant To be Multiplied: </label>
  <select id="math" name="options">
    <option value="nothing">Please select a constant</option>
    <option value="pie" <?php if (!empty($choice) && $choice == 'Option1')  echo 'selected = "selected"'; ?>>Pi</option>
    <option value="econs"<?php if (!empty($choice) && $choice == 'Option3')  echo 'selected = "selected"'; ?>>e</option>
    <option value="ratio" <?php if (!empty($choice) && $choice == 'Option3')  echo 'selected = "selected"'; ?>>Golden Ratio</option>
    <option value="root" <?php if (!empty($choice) && $choice == 'Option4')  echo 'selected = "selected"'; ?>>Root 3</option>
  </select>
 <br> <label for="fname">Number To be Multiplied: </label><input type="text" id="fname" name="value"><br>
  <input type="submit">
</form>

<?php
while ($_SERVER["REQUEST_METHOD"] == "POST"){        
    if (ctype_alpha($_POST["value"])){
     echo "Please only input numbers";
         exit;

 } else if (($_POST["value"] <= 0)){
     echo "Please Enter Positive numbers only";    
        exit;
} 
else if ($choicex = 'Option1'){
 echo ($_POST['value']*pi());
 exit;
}    
else if ($choice = 'Option2'){
    echo ($_POST['value']*exp());
 exit;
    
}

}
?>

[ginerjm]

PUT your php at the start.  Save the html for the end.

Your php code embedded in the options is wrong the "choice" will be Pi or econs, not Option1 or 2 or 3.  Basically , the value value.

You will not have a $_GET value.  Your form is using POST

[tridentmist]

4 minutes ago, ginerjm said:

PUT your php at the start.  Save the html for the end.

Your php code embedded in the options is wrong the "choice" will be Pi or econs, not Option1 or 2 or 3.  Basically , the value value.

You will not have a $_GET value.  Your form is using POST

OK thanks, even when i change the values from "choice" to "pie" and "econs" it only goes to the pie option. How do I make it check to see if "e" was selected. and i fit was, then do the math for that option

Edited March 27, 2020 by tridentmist

[ginerjm]

First  change the while to an if.  Then put all that at the top of your script and only execute it if your detect that the POST method has been submitted. If not, that's when you fall down to output the html part.