Retrieve a variable whos name is has another variable in it - php

Question

Dunno if the title makes sense, but I have a variable which would to put it in basic terms would be called like this:
$_POST['something'+$variable2]
I have a form which is for editing selected records, this form contains entries for all previously selected records:
<form name="input" action="editcar.php" method="POST">
<input type="submit" value="Yes">
while($row = mysqli_fetch_assoc($result))
{
echo'
</div>
<table style="color:white">
<tr>
<td style="text-align:right">Manufacture:</td><td><input type="text" name="manufacture'.$row['carIndex'].'" value="'.$row['make'].'"></td>
<td style="text-align:right">Model: </td><td><input type="text" name="model'.$row['carIndex'].'" value="'.$row['model'].'"></td>
</tr>
<tr>
<td style="text-align:right">Colour: </td><td><input type="text" name="colour'.$row['carIndex'].'" value="'.$row['colour'].'"></td>
<td style="text-align:right">Reg: </td><td><input type="text" name="reg'.$row['carIndex'].'" value="'.$row['Reg'].'"></td>
</tr>
<tr>
<td style="text-align:right">Price: </td><td><input type="text" name="price'.$row['carIndex'].'" value="'.$row['price'].'"></td>
<td style="text-align:right">Mileage: </td><td><input type="text" name="mileage'.$row['carIndex'].'" value="'.$row['miles'].'"></td>
</tr>
<tr>
<td style="text-align:right">Max MPH: </td><td><input type="text" name="mph'.$row['carIndex'].'" value="'.$row['mph'].'"></td>
<td style="text-align:right">MPG: </td><td><input type="text" name="mpg'.$row['carIndex'].'" value="'.$row['mpg'].'"></td>
</tr>
</table>
</form>
</div> ';
}
?>
</form>
The form is looped for each record previously chosen, to enable mass editing. The isue arouses when I realised I'd have multiple inputs with the same name, so I did:
<input type="text" name="model'.$row['carIndex'].'" value="'.$row['model'].'">
Placing the primary key of the record it was currently tired to on the end of it's name. Which seemed like a logical way to go about things.
However now I need to call these variables to place in the mysql query and I dunno how to do that, or even if I can.
I have the selected records saved in an array so I have:
foreach ($postid as $carID)
{
$query = "stuff";
mysqli_query($db, $query);
}
Each loop has $carID containing the variables that was put on the end of the form input names.
So something like:
$_POST['something'+$variable2]
is all I can think of but doesn't work.
Any method that works for my overall code is welcome not just a solution to the issue I've made.

Answer 1

Actually your way should work. Just replace the + with . in $_POST['something'+$variable2].
My tip is: use an array as name in your html instead:
<input type="text" name="model[]" value="'.$row['model'].'">
On php-Side you can loop through all $_POST['model'] since its an array now.
You can add the index for every entry in your html, too:
<input type="text" name="model['.$row['carIndex'].']" value="'.$row['model'].'">

Answer 2

PHP uses a dot for concatenation, not + like Java and Javascript:
$_POST['something' . $variable2]

Answer 3

Try something like this:
<form ...>
<?php
while($row = mysqli_fetch_assoc(...):
$index = $row['carIndex'];
?>
<input type="text" name="carmodel[<?php echo $index?>][model]" value="<?php echo $row['model'] ?>">
<?php endforeach; ?>
</form>
This way you will have the data stored in $_POST['carmodel'] as an array indexed by carIndex value as the structure of data in $_POST is defined by names of inputs, here you will have names likee carmodel[1][model] for example so then in post it will be in $_POST['carmodel'][1][model]
you can read here as well
How would I create this array structure in an HTML form?