PHP Forum

**jcrensha627** · 08:28 PM

Hey everyone im tryin to code something which may be simple but ive attempted and failed. Im creating a stock market simulation website using php and phpmyadmin. In the table JAME_PH i have this-

id symbol shares volume price
53 JAME 0 50.00

I now want to do price change, ive already gotten volume to change and work (the sum of all shares) but now i would like the price to change due to volume .01% at a time, so it would really be a .01% change for every 10 shares traded. I'm lost on how to do this calculatio in php. below i started some code think i was goin in the right direction... all help is appreciated!!!!

here is the code on my buy page as of now

PHP Code:


			
<html>
<body>
Go Back to<a href="index.php">Your Portfolio</a>
<br>
<br>
Are you sure you want to buy shares in JAME? (Total Below)
<br>
<br>
 
<?php
ob_start();
include("config.php");
 
$username = $_COOKIE['loggedin'];
if (!isset($_COOKIE['loggedin'])) die("You are not logged in, <a href=../login.html>click here</a> to login.");
 
// connect to the mysql server
$link = mysql_connect($server, $db_user, $db_pass)
or die ("Could not connect to mysql because ".mysql_error());
 
// select the database
mysql_select_db($database)
or die ("Could not select database because ".mysql_error());
 
$get_my_basket = mysql_query("SELECT `symbol`, `price` FROM `JAME_PH` WHERE `symbol`='".JAME."'");
 
  $total_cost = 0;
  $JAME = 0;
  $quantity = $_POST['quantity'];
 
 
while($my_basket = mysql_fetch_array($get_my_basket))
{
  if($my_basket['symbol']=='JAME') $JAME++;
 
  $total_cost += $my_basket['price'] * $quantity;
}
 
echo 'You have selected: ';
if($JAME > 0)
{
   echo $quantity.' JAME shares, ';
}
else
{
echo 'Your Basket it Empty';
}
$total_cost = number_format($total_cost,2);
 
echo ' and it will cost you $'.$total_cost;
 
 
$query = "select `shares` from JAME_PH";
$result = mysql_query($query);
  
 
$volume = $_POST['quantity'];
 
while($row = mysql_fetch_array($result))
{
    $volume += (int)$row['shares'];
    echo 'id '.$row['id'];
    echo 'symbol '.$row['symbol'];
    echo 'shares '.$row['shares'];
    // add to the volume and print
    echo 'volume = '.$volume;
    echo 'price = '.$row['price'];
}

//  I want to make a new query and new result here

$query2 = "select `price` from JAME_PH WHERE `id`=53";
$result2 = mysql_query($query);
  
 
$price= 50.00;
 
while($row = mysql_fetch_array($result2))
{
    //  SO LOST ON WHERE TO BEGIN. i want it so every time a user trades(buys) 10 shares the price (50.00) will increase by .01% - so when someone buys 10 shares 50.00 will change to 50.05 

  //  50.00 * .01 = 0.5 now add the .5 to 50.00 to get 50.05 and insert into the table at id 53 under price!!!. I wish i new where to begin. THANKS IN ADVANCE ANYONE!!!!!
}

 
$insert = mysql_query("insert into trades values ('NULL', 'JAME', '".$_POST['quantity']."', '$total_cost', '$username' )")
or die("Could not insert data because ".mysql_error());
 
$insert2 = mysql_query("insert into JAME_PH values ('NULL', 'JAME', '".$_POST['quantity']."', $volume, '$username',$increase, '$username' )")
or die("Could not insert data because ".mysql_error());
 
ob_end_flush();
?>
 
 
<br>
<br>
Visit<a href="index.php">Your Portfolio</a> to see your purchases.
 
</body>
</html

**NullPointer** · 04-08-2009, 08:26 PM

So you are trying to "change" the price by .01% (.0001) for every 10 shares traded?
For an increase:

PHP Code:


			
$newPrice = 0.00000;

$newPrice = (float)($price * 1.0001);

**jcrensha627** · 04-08-2009, 08:32 PM

thanks pointer!!

but how does this take in consideration only changing when a user buys 10 shares??? or does it?? whats fllat btw? THANKS!!

$newPrice = 0.00000;
$newPrice = (float)($price * 1.0001);

i guess im looking for an if or something?? maybe not?

if post quantity is >10 ($price * 1.0001);

**NullPointer** · 08:47 PM

You'd have to track how many shares are traded.

PHP Code:


			
if($sharesTraded % 10 == 0 && $sharesTraded > 0)

{

     $newPrice = 0.00000; //specifying precision

     $newPrice = (float)($price * 1.0001);

}

Float is a datatype, specifically any real number, including decimal values (to a certain point). If you were writing this code in java you would be painfully aware of datatypes. In PHP however datatypes are more or less transparent, however when dealing with floating point numbers you sometimes need to cast the right side of an equation to a float so PHP won't truncate all of the values to the right of the decimal.

% by the way is called modulus. It returns the remainder of a division. So 14 % 10 is 4. 20 % 10 is 0.

If you plan on storing that value in the database, make sure you don't do it as an INT otherwise you'll lose all of the values to the right of the decimal. Store it either as a float, or multiple the value by 100 before entering it and divide it by 100 as soon as you retrieve it (if you don't mind losing cent fractions).

**jcrensha627** · 04-08-2009, 08:43 PM

Quote:

Originally Posted by NullPointer

You'd have to track how many shares are traded.

PHP Code:


			
if($sharesTraded % 10 == 0 && $sharesTraded > 0)
{
     $newPrice = 0.00000; //specifying precision
     $newPrice = (float)($price * 1.0001);
}

Float is a datatype, specifically any real number, including decimal values (to a certain point). If you were writing this code in java you would be painfully aware of datatypes. In PHP however datatypes are more or less transparent, however when dealing with floating point numbers you sometimes need to cast the right side of an equation to a float so PHP won't truncate all of the values to the right of the decimal.

% by the way is called modulus. It returns the remainder of a division. So 14 % 10 is 4. 20 % 10 is 0.

wow thanks for the info pointer, def undestand this better. so is this code good to go? i think i need to insert new price into the table now correct???? and how would i keep track of shares traded? is that line if($sharesTraded % 10 == 0 && $sharesTraded > 0) doin it for me? THANKS ALOT MAN. amazing

**NullPointer** · 04-08-2009, 08:50 PM

The code is mostly an example of how you would do it, not an actual implementation.

To track the number of shares traded just initialize $sharesTraded to zero and increment it each time a trade occurs.

PHP Code:


			
$sharesTraded = 0;



//trade occurs



$sharesTraded++;