How to use method $_POST in php

index.php:

<form action="post.php" method="POST">
  <input type="text" name="option_<?php echo $i ?>" value="" />
  <input type="submit" name="btnSubmit" value="submit">
</form>

The $i variable is a sequence running from 1 to $n.

post.php:

if(isset($_POST['btnSubmit']))
{
  $option_name = ???;
}

How do I get the text that was posted for each option?

Why not use PHP arrays for this?

<form action="" method="POST">
 <input type="text" name="option[]" value="" />
 <input type="submit" name="btnSubmit" value="submit">
</form>

In the file it is posted to:

if(isset($_POST['btnSubmit']))
{
   foreach ($_POST['option'] as $i => $value)
   {
       echo "Option $i is $value\n";
   }
}

<form action="" method="POST">
 <input type="text" name="option_<?php echo $i ?>" value="" />
 <input type="submit" name="btnSubmit" value="submit">
</form>

this is your form

you may store it to a variable and use that variable in $_POST

$name= "option_".$id;

if(isset($_POST['btnSubmit']))
{
 $option_name = $_POST[$name];
}

in the file post.php you can do

 $option_name = $_POST['option_1'];

and then $option_name has the value of the input field with name option_1

if $i is a seuqennce, you could asve the last $i value in an hidden field as a counter:

//in index.php
for ($i = 0; $i < $max; $i++){
     <input type="text" name="option_<?php echo $i ?>" value="" />
     if ($i = $max -1){//it's the last iteration, save the counter
          <input type="hidden" name="counter" value="$i">
     }
}

//in post.php

$counter = $_POST['counter'];
$options = array();
for ($i = 0; $i < $counter+1; $i++){
     $options[] = $_POST["option_$i"];
}