php calculation keeps getting the answer as 0-CodePudding

this is the index.php file

if(isset($_POST['submit']))
{
    echo header('Location:answer.php');
}
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div >
        <form method="post">
            <div >
                <label> Insert P value </label>
                <input type="text" name="p" placeholder="please insert your P value">
</div>
<br>

<div >
    <label> Insert R value </label>
    <input type="text" name="r" placeholder ="please insert your R value ">
    
</div>
<br>
<div >
    <label> Insert your N value </label>

    <input type="text" name="n" placeholder=" please insert your N value">

</div>
<br>
    <button type="submit" name="submit" > Submit </button>
</body>
</html>

this is the answer.php file

<?php

$p=isset($_POST['p'])?$_POST['p']: " ";
$r=isset($_POST['r'])?$_POST['r']:" ";
$n=isset($_POST['n'])?$_POST['n']: " ";
$si=(int)$p*(int)$r*(int)$n/100;
echo "Hello this is the final answer ".$si;
?>

i want the answer to be displayed in another page that is answer.php but whatever number i am inserting i keep getting the answer as 0. Please help and thank you.

CodePudding user response：

You need to make your form post directly to answer.php. By making it post to itself and then redirecting you're losing all the submitted data - it's sent to your index page and then not transmitted again to the answer page. The redirect causes a separate GET request and doesn't contain any of the submitted data.

The other alternative is to move all the logic into index.php and not bother with a separate script at all.