calculating in php

[TGM]

referring again with to the restaurant db. I want to calculate the total price for the order.

 

how can I calculate the total price of an order..I know its 'amount' x 'quantity' but how to code this..

[premiso]

$total = ($amount * $quantity);

[corbin]

premiso, why the parenthesis?

[Ken2k7]

premiso, why the parenthesis?

Didn't you get the memo? It's the new trend going around. Everyone's doing it nowadays.

 

People started:

$query = ("SELECT * FROM table");

[DarkWater]

(let ((amount 5.00) (quantity 3))
  (* amount quantity))

 

Ahhhhhhhhhhhh!

[premiso]

premiso, why the parenthesis?

 

I always do math operations inside parans. Just a habit. Even in my math classes since I have learned what the parans did and got marked for not using them I just do it. Order of Operations is how I see it. Having them in there for math operations is nice because you know what you write should be executed in the right order.

 

But I only use it on math operations.

[TGM]

$total = ($amount * $quantity);

 

aight this is what I got

 

<?php
$result = mysql_query("SELECT * FROM orders ORDER BY `id` DESC LIMIT 1");

echo "<table border='1'>
<tr>
<th>Item</th>
<th>Quanity</th>
<th>Price per unit</th>
<th>Extra</th>
</tr>";

while($row = mysql_fetch_array($result))
  {
  echo "<tr>";
  echo "<td>" . $row['item'] . "</td>";
  echo "<td>" . $row['quanity'] . "</td>"; //yes its quanity not quality
  echo "<td>" . $row['price'] . "</td>";
  echo "<td>" . $row['extra'] . "</td>";
  echo "</tr>";
  }
echo "</table>";


echo"<br><div align='center'><em>YOUR TOTAL BILL IS:</em></div>
<HR WIDTH='75%' SIZE='3' NOSHADE><br />";

//option 1
$result = $row['quanity'] * $row['price']; //doesnt work...outputs 0

//option 2
$result = $quanity * $price; //doesnt work..says Undefined variable: price
echo "<p>Bill: $result</p>";


mysql_close($db);
?>

 

It displays the last order but doesnt displays the calculation..for example if an item cost price= 2.25 and amount=2 should be 2.50 (i tink!lol) the option 1 code gives 0 and the option 2 gives an error..how can I read the value from the 'price' and the 'quantity' field?

[Ken2k7]

Oi... learn PHP.

 

[corbin]

premiso, why the parenthesis?

 

I always do math operations inside parans. Just a habit. Even in my math classes since I have learned what the parans did and got marked for not using them I just do it. Order of Operations is how I see it. Having them in there for math operations is nice because you know what you write should be executed in the right order.

 

But I only use it on math operations.

 

 

 

Hrmmm never seen anyone do that before ;p.

[Ken2k7]

corbin - I'm sure you've seen something like this before:

$random_number = intval($_POST['random_number']);
$some_formula_result = ($random_number + 4) * 4;

 

I just made that up, but you get the point with parentheses. I'm just being an ass. I know what you meant.

[Mark Baker]

It displays the last order but doesnt displays the calculation..for example if an item cost price= 2.25 and amount=2 should be 2.50 (i tink!lol) the option 1 code gives 0 and the option 2 gives an error..how can I read the value from the 'price' and the 'quantity' field?

:polite mode enabled:

 

Because after while($row = mysql_fetch_array($result)) has finished looping, $row no longer contains record data.

 

And because your $result = $row['quanity'] * $row['price']; with an empty row is overwriting the value of the $result resultset returned by your database query, you can't even loop again.

 

Calculate the value of each line in your loop.

[corbin]

corbin - I'm sure you've seen something like this before:

$random_number = intval($_POST['random_number']);
$some_formula_result = ($random_number + 4) * 4;

 

I just made that up, but you get the point with parentheses. I'm just being an ass. I know what you meant.

 

 

 

But the parenthesis are needed there .

[premiso]

Hrmmm never seen anyone do that before ;p.

 

Doesn't surprise me I always had to do that in Pre-Calc to keep my orders or operations correct or else I would screw something up. It just kept me straight. My teacher was always bugged by it, but he could not dock me cause it got the right solution.

 

I am decent with math, I just suck at organization lol.

 

$some_formula_result = ($random_number + 4) * 4;

 

You see, I would have written that like:

$some_formula_result = (($random_number + 4) * 4);

 

and that is what confuses corbin about my style.