PHP - Math Function

I am trying to create a math equation inside a variable but I am struggling to achieve the desired result.

On one php page I have this:

 $x = "date('Y')";
 $y = "1989";
 $description = "In this classic lecture which was delivered over $x - $y years ago, etc etc.....";

On my main page I have linked to the above and also $description but the result I am getting is:

In this classic lecture which was delivered over date('Y') - 1989 years ago,

 

I want to create a variable so I don't need to go back every year and change the description. Is this possible?

Robert

 

question here...

say we have a string coming from a form, already verified that its numeric/mathmatical(+-*/) how can we then process that into an answer without using eval?

Code: [Select]
$string='1+2*3';
echo process($string); #7

Quote

If eval() is the answer, you're almost certainly asking the wrong question. -- Rasmus Lerdorf, BDFL of PHP

Hey.   So imagine this example...  

class FormulaEvaluator {
...... //Construct & variables here..
 
public function exec() {
//Missing some lines here, but you get the idea
$formula = $this->formula;
$context = (array) $this;
ob_start();
$res = eval('return ' . $formula . ';');
}
}
 
$formulaEvaluator = new FormulaEvaluator();
$formula = '10 * (($Test * 2) + ($Test2 / 3))';
$formulaEvaluator->formula = $formula;
$formulaEvaluator->Test = 20000;
$formulaEvaluator->Test2 = 300000;
$res = $formulaEvaluator->exec();
echo $res; //1400000

  The code we have is working as intended, but we want to avoid using eval. I know it's a pretty common question, and the answer is usually the same, but is there any way to do something similar without using eval?

Website: http://novacms.vacau.com/index.php

I'm trying to make a calculator for this game I play, it's fully developed, but with one bug. It doesn't do the math right.

$goal = The amount of EXP (Experience Points) someone wants to get
$exp = The amount of EXP they currently have
$npcs_exp["exp"] = The amount of EXP the monster has

But, when they enter in the information, the calculation is all screwed up. When I do it, it seems to give me the same number EACH time.

The part where the calculation "goes down". Remember, I'm trying to see how many times you need to kill a NPC to achieve your goal.


//math
$npc_exp_extract = mysql_query("SELECT exp FROM npcs WHERE name='$npc'");
$npcs_exp = mysql_fetch_assoc($npc_exp_extract);

$amount = $goal / $npcs_exp["exp"];


Full code:


<?php
$exp = $_POST["exp"];
$npc = $_POST["npc"];
$goal = $_POST["goal"];

mysql_connect("removed", "removed", "removed");
mysql_select_db("a2248602_npcs");

if(!$goal || !$npc || !$exp)
{
echo "<center><form action='index.php' method='POST'>GOAL: <input type='text' name='goal'> Current XP: <input type='text' name='exp'>";
echo "NPC: <select name='npc'>";

$npc_extract = mysql_query("SELECT * FROM npcs");
while($npcs = mysql_fetch_assoc($npc_extract))
{
 echo "<option name='". $npcs['name'] ."'>". $npcs['name'] ."</option>";
}

echo "</select> <input type='submit'></form></center>";
}
else
{
//math
$npc_exp_extract = mysql_query("SELECT exp FROM npcs WHERE name='$npc'");
$npcs_exp = mysql_fetch_assoc($npc_exp_extract);

$amount = $goal / $npcs_exp["exp"];

if($amount=="1")
{
echo "You will need to kill a <b/>". $npc ."</b> <b>". $amount ."</b> more time. You earn ". $npcs_exp["exp"] ." XP for each kill from this NPC. | <a href='index.php'>Do another</a><br/><br/>";
}
else
{
echo "You will need to kill a <b/>". $npc ."</b> <b>". $amount ."</b> more times. You earn ". $npcs_exp["exp"] ." XP for each kill from this NPC. | <a href='index.php'>Do another</a><br/><br/>";
}
}

echo "<center>Made by Zaros from <a href='creation-x.net'>Creation-X</a></center>";
?>


Mod edit: DB credentials removed.

I'm using this code to get me the variables to a select box on a register page:
$vars['user-birthdate-years'] = array(_VARS_USER_CHOOSE_ => "Please choose", _VARS_USER_NONE_ => _VARS_USER_UNDEF_); for ($i = date('Y') - 18; $i > date('Y') - 75; --$i) { $vars['user-birthdate-years'][$i] = "$i"; }

This gives me this result in the page source:
<select name="birthyear" class="date"><option value="-2" selected="selected">Please choose</option><option value="1997">1997</option><option value="1996">1996</option><option value="1995">1995</option><option value="1994">1994</option><option value="1993">1993</option><option value="1992">1992</option><option value="1991">1991</option><option value="1990">1990</option><option value="1989">1989</option><option value="1988">1988</option><option value="1987">1987</option><option value="1986">1986</option><option value="1985">1985</option><option value="1982">1982</option><option value="1981">1981</option><option value="1980">1980</option><option value="1979">1979</option><option value="1978">1978</option><option value="1977">1977</option><option value="1976">1976</option><option value="1975">1975</option><option value="1974">1974</option><option value="1973">1973</option><option value="1972">1972</option><option value="1971">1971</option><option value="1970">1970</option><option value="1969">1969</option><option value="1968">1968</option><option value="1967">1967</option><option value="1966">1966</option><option value="1965">1965</option><option value="1964">1964</option><option value="1963">1963</option><option value="1962">1962</option><option value="1961">1961</option><option value="1960">1960</option><option value="1959">1959</option><option value="1958">1958</option><option value="1957">1957</option><option value="1956">1956</option><option value="1955">1955</option><option value="1954">1954</option><option value="1953">1953</option><option value="1952">1952</option><option value="1951">1951</option><option value="1950">1950</option><option value="1949">1949</option><option value="1948">1948</option><option value="1947">1947</option><option value="1946">1946</option><option value="1945">1945</option><option value="1944">1944</option><option value="1943">1943</option><option value="1942">1942</option><option value="1941">1941</option></select>

Problem: When running the php code at the top it miss two years in the span as you see in the page source below, the year 1983 and 1984 is completely missing in the page source. Why is this happening, could the php code be corrected or is there a workaround in php for the missing years bug I seem to have found?

I really appreciate any help on this!
Edited by Drezzzer, 12 January 2015 - 05:16 AM.

Hello all.

Trying this again.  I would like to implement a simple math formula based on a date, but not sure how to do that exactly.

I run a sports league, and want to calculate fees based upon a fixed date.  Prior to 'some date' use this calculation, but after this date, add late fees using 2nd calculation.  In my code there are two fields:  $earlyteam and $lateteam.  I need $lateteam to kick in after 'some date'.  Help?
Code: [Select]
//calculate Fees
  $size = $lSize['size'];
  switch($size)
  {
    case 2:
         $base = 150;
         $size = 3;
           break;
    case 4:
         $base = 330;
         $size = 6;
           break;
    case 6:
         $base = 550;
         $size = 10;
           break;                 
   default: die ("invalid league size");
  };
 
   $earlyTeam = $base;

   {
     $e_each = $earlyTeam / $pCount;
     $lateTeam = $earlyTeam * 1.10;
     $l_each = $lateTeam / $pCount;
   } 

Having to go into somebody else's code yet again! Gah! Originally the totaling page just subtracted a flat discount. But now the client wants to be able to subtract percentage discounts and 'per item' discounts. In the discount table I added a field to determine whether the discount chosen is to be applied as flat off total, flat per item, % off total, and % off each item. I also entered a field that can have a class id, in case this discount is only for that class. (the intention being that otherwise the discount is on anything)

I've got a session variable that generates something like : Array ( [217] => 1 [215] => 2 )
meaning 1 person in class #217, and 2 people in class 215.

$_SESSION['s_to_be_added'] = array_filter($_POST['participantqty']);

Then on the page I'm concerned with, I've been trying to write the script. I know I still need some math stuff figured out
 But how do I take the array, do the math, and then generate an overall cost for the whole thing? and this is just  the discounting? I don't even have a clue how to work in delimiting it if there's a class id.. did any of that make sense?

Code: [Select]
<?php

// the above is the array I want to use to 
$passed_array = array_filter($_SESSION['s_to_be_added']);

// this is the discount 'code' the user entered.
$discount = mysql_escape_string($_POST['discount']);

// just a donation added after everything.
$donation = mysql_escape_string($_POST['donation']);

// finding the discount that matches the discount 'code' entered.
$query_selectAllItems_events = "SELECT discount_amount,discount_type,workshop_link_1 FROM tbl_discount where discount_value = '$discount'";

    $result_all_events = mysql_query($query_selectAllItems_events);
$numRows_all_events = mysql_num_rows($result_all_events);
$num=mysql_num_rows($result_all_events); 
$z_row = mysql_fetch_array($result_all_events);
        
        // this is just a number: 1, 20, 90 etc.
        $discount_amount = $z_row['discount_amount'];
        
        /*this is 1,2,3,4 - for each type of discount 1- flat 2- flat per item
        3- discount on all, 4- discount per item */
        $discount_type = $z_row['discount_type'];
        
        // the workshop id if the discount is onlyh for this workshop
        $discount_link_1 = $z_row['workshop_link_1'];
        
        // just a description
$discount_name = $z_row['discount_name'];

        
if ($discount_type ==1) {
            /* flat discount on total here */
            $total = mysql_escape_string($_POST['total']);

$final_total = ($total - $discount_amount);
$final_total = ($final_total + $donation);
        }
        
        elseif ($discount_type ==2)) {
            /*  discount per item total here */
$total = mysql_escape_string($_POST['total']);

$final_total = ($total - $discount_amount);
$final_total = ($final_total + $donation);
        
        }
        
        elseif ($discount_type ==3)) {
            /* percentage discount on total here */
$total = mysql_escape_string($_POST['total']);

$final_total = ($total * ($discount_amount/100));
$final_total = ($final_total + $donation);
        
        }
        
        elseif ($discount_type ==4)) {
            /* percentage discount per item here */
$total = mysql_escape_string($_POST['total']);

$final_total = ($total * ($discount_amount/100));
$final_total = ($final_total + $donation);
        
        }
        
        ?>

I can not seem to figure out how to do this..

I just need to add 100+99+98+97+96...+1 

no you can not do 100! because that multiples them =]

 In a past post I mentioned that my ultimate goal of this is code is to query our SQL system for a start date and a stop date.  At both of those points, the query would spit out a value for that the column based on a determined time and day.  The first point would be a min or minUsage.  The second point would be max or maxUsage.  These points will be subtracted from each other to create a value.  See below.  Not that it matters but the value is the amount of kWh per months.     So, now, Min and Max are both defined below but I suspect the value is being truncated for each.  Also, Im not sure the calculation is right because I am getting an unexpected solution.  I am asking that someone look at this code and tell me what should be happening mathematically.  (down to the accuracy of the answer (pre calculation and post calculation)  It would help me better see my mistakes.    To give you an example of some data.  I have    Max ( or July 31)   total_energy_a =26872 total_energy_b =27619 total_energy_c =26175   Min ( or July 1) total_energy_a =20347 total_energy_a =20914 total_energy_a =19808   Max - Min  19597   With these numbers, would you expect this outcome from this code?   Thanks.

<?php
$sql = ";WITH TOTAL_KWH_SUMMER AS
(
SELECT CONVERT(VARCHAR(10),cdate,111)AS trans_date, datepart(hh, cdate) as trans_hour, comm_id, 
MIN((total_energy_a+total_energy_b+total_energy_c)/100) AS minUsage, 
MAX((total_energy_a+total_energy_b+total_energy_c)/100) as maxUsage, repeated
  FROM [radiogates].[dbo].[purge_data] 
  where comm_id='$comm_id' 
  group by comm_id, CONVERT(VARCHAR(10),cdate,111), datepart(hh, cdate), repeated
)
SELECT *, datepart(weekday, trans_date) as trans_date_day, datepart(month, trans_date) as 

trans_date_month, maxUsage - minUsage as totalUsage
FROM TOTAL_KWH_SUMMER 

where datepart(weekday, trans_date) IN ('1', '2', '3', '4', '5', '6', '7') 
AND DATEPART(MONTH, trans_date) IN ('5','6','7','8','9','10') 
and trans_date BETWEEN '$startdate2 00:00:01' AND '$enddate2 24:00:00' and repeated <> '1' ";
$query = sqlsrv_query($conn, $sql);if ($query === false){  exit("<pre>".print_r(sqlsrv_errors(), true));}while ($row = sqlsrv_fetch_array($query)){  	$sumUsageKWH += $row[totalUsage];}sqlsrv_free_stmt($query);?> 

The title may not fit but only thing i could think of.

I am pulling data from MSSQL database table.... I need everything from that table but i need to do some basic math funcitons to the resulting data.

So the quesiton is should i do the math for this in the SQL query if so how do i pull all fields and do the math in an effcient way.

Or should i let php do the math for me after i get all the data i need. 

If it is better to use php how can i do this in a while loop and get the math result and not a printed equation.

Just looking for a few pointers never had to do math before with php

Hi guys!

Am trying to get hold of a PHP Math Expression Parser that follows correct precedence and executes custom functions. Can somebody share his scripts? or lead me to the right directions?

Hope you can help! Thanks a lot! My boss is gonna kill me soon. This is 1 week overdue already.

Jon

What is the correct way to right a simple maths question

i have my total as:
<?php echo $row['total'];?>

i have my another number as:
<?php echo $row['user_credit']; ?>

but what i want to do is subtract the user_credit from the total and save it as a new variable called 'credits_used' but im unsure how to write it

do i do it like
$row['total'] - $row['user_credit'] = $row['credit_used'];

Thank for any help

My code is

$answer = (1/212500);
output is

4.90205690308E-6

while I need I output as
0.00000470588

Please help, and tell me what is the specific problem,

This topic has been moved to PHP Math Help.

http://www.phpfreaks.com/forums/index.php?topic=310665.0

I am doing some simple math and it is spitting out very odd results.

//First Loop to get the values
$get_values = mysql_query("SELECT * FROM table");
while($values = mysql_fetch_array)){
$value_one += $values[value_one];
$value_two += $values[value_two];
}
$difference = $value_one - $value_two;
echo"$value_one - $value_two = $difference;

The database field types are DECIMAL(10,2). The output of the individual values is echoing the correct 0.00 format but after it loops for awhile the difference seems to come out differently. and have close to 5 or 6 places after the decimal. if i echo the values as it is looping and adding them it seems to not be adding correctly either. What am I doing wrong?