Calculating Hours with a From and To Time?

Jts · February 23, 2011

Hi,

I've just started learning php and for my first project i'm doing a database app that tracks employee time and commissions.

I have a form with a dropdown box to select start time and end time. I'm then converting it to 24 hr time and trying to do the math to figure out how many hours have been worked. The problem is that when I do the $hours = $endtime - $starttime; it rounds to a whole number instead of a decimal so even if they worked 6.5hrs it shows as 6 hrs. I'm not sure what I should convert the time to so that the math will figure out the decimal value.

Here is the form code and below is the time.php code. Pardon the mess. Some of the code in the time.php file is just so I can better follow what is happening with all this php stuff!!

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>Employee Timesheet</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  </head>
  <body>
      <form method="post" action="time.php">
<?php
    $hostname="hostname";
    $db_username="dbusername";
    $db_password="dbpassword";
    $db_name="dbname";

    mysql_connect($hostname, $db_username, $db_password) or die (mysql_error());
    mysql_selectdb($db_name);
    $query = "SELECT * FROM employees";
    $result = mysql_query($query);
?>
      

Name:
<select name="employee">
    <option value = "">Select One</option>
<?php

while($row = mysql_fetch_array($result)){
    echo '<option value = "'.$row['employee_ID'].'">'.$row['username'].'</option>';
};
?>
</select>
    <br />
    <br />
Date:
    <select name="month" >
        <option value ="">Month</option>
        <option value ="01">January</option>
        <option value ="02">February</option>
        <option value ="03">March</option>
        <option value ="04">April</option>
        <option value ="05">May</option>
        <option value ="06">June</option>
        <option value ="07">July</option>
        <option value ="08">August</option>
        <option value ="09">September</option>
        <option value ="10">October</option>
        <option value ="11">November</option>
        <option value ="12">December</option>
      </select>

    <select name="dt">
        <option value=''>Day</option>
        <option value='01'>01</option>
        <option value='02'>02</option>
        <option value='03'>03</option>
        <option value='04'>04</option>
        <option value='05'>05</option>
        <option value='06'>06</option>
        <option value='07'>07</option>
        <option value='08'>08</option>
        <option value='09'>09</option>
        <option value='10'>10</option>
        <option value='11'>11</option>
        <option value='12'>12</option>
        <option value='13'>13</option>
        <option value='14'>14</option>
        <option value='15'>15</option>
        <option value='16'>16</option>
        <option value='17'>17</option>
        <option value='18'>18</option>
        <option value='19'>19</option>
        <option value='20'>20</option>
        <option value='21'>21</option>
        <option value='22'>22</option>
        <option value='23'>23</option>
        <option value='24'>24</option>
        <option value='25'>25</option>
        <option value='26'>26</option>
        <option value='27'>27</option>
        <option value='28'>28</option>
        <option value='29'>29</option>
        <option value='30'>30</option>
        <option value='31'>31</option>
    </select>

Year:
    <select name="year">
        <option value='2010'>2010</option>
        <option selected value='2011'>2011</option>
        <option value='2012'>2012</option>
        <option value='2013'>2013</option>
        <option value='2014'>2014</option>
    </select>
    <br />
    <br />
Time: 
    <select name ="starttime_hr">
        <option value=''>Hour</option>
        <option value='01'>01</option>
        <option value='02'>02</option>
        <option value='03'>03</option>
        <option value='04'>04</option>
        <option value='05'>05</option>
        <option value='06'>06</option>
        <option value='07'>07</option>
        <option value='08'>08</option>
        <option value='09'>09</option>
        <option selected value='10'>10</option>
        <option value='11'>11</option>
        <option value='12'>12</option>
    </select>
    <select name ="starttime_min">
        <option value=''>Min</option>
        <option selected value='00'>00</option>
        <option value='15'>15</option>
        <option value='30'>30</option>
        <option value='45'>45</option>
    </select>
    <select name ="starttime_ampm">
        <option value='am'>A.M.</option>
        <option value='pm'>P.M.</option>
    </select>
To:
    <select name ="endtime_hr">
        <option value=''>Hour</option>
        <option value='01'>01</option>
        <option value='02'>02</option>
        <option value='03'>03</option>
        <option selected value='04'>04</option>
        <option value='05'>05</option>
        <option value='06'>06</option>
        <option value='07'>07</option>
        <option value='08'>08</option>
        <option value='09'>09</option>
        <option value='10'>10</option>
        <option value='11'>11</option>
        <option value='12'>12</option>
    </select>
    <select name ="endtime_min">
        <option value=''>Min</option>
        <option selected value='00'>00</option>
        <option value='15'>15</option>
        <option value='30'>30</option>
        <option value='45'>45</option>
    </select>
    <select name ="endtime_ampm">
        <option value='am'>A.M.</option>
        <option selected value='pm'>P.M.</option>
    </select>
    <br />
    <br />
Sold:
    <input type="text" name="sold"/>
    <br />
    <br />
Upgrades:
    <input type="text" name="upgrades"/>
    <br />
    <br />
    <input type="submit" value="Submit"/>

</form>



  </body>
</html>

time.php Code!!

<?php
$sttime = $_POST['starttime_hr'].":".$_POST['starttime_min']." ".$_POST['starttime_ampm'];
$endtime = $_POST['endtime_hr'].":".$_POST['endtime_min']." ".$_POST['endtime_ampm'];
$sttime_24 = date("H:i:s", strtotime("$sttime"));
$endtime_24 = date("H:i:s", strtotime("$endtime"));
echo "$sttime"." To "."$endtime";
echo "<br />";
echo "$sttime_24";
echo "<br />";
echo "$endtime_24";
echo "<br />";
echo "Hours Worked:";
$hours = $endtime_24 - $sttime_24;

echo "$hours";
?>

Thanks in advance for helping this Newbie!!

Jonathan Smith

PFMaBiSmAd · February 23, 2011

$endtime_24 and $sttime_24 are formatted strings that consist of parts that have three different number bases (24hours,60minutes,60seconds.) You cannot perform math on strings that contain non-numeric characters (computers treat the first non-numeric character as a stop character) and you cannot perform math on numbers unless they are all in the same number base.

I recommend getting both values into the number seconds they correspond to in order to perform the math.

Jts · February 23, 2011

Thanks for the clarification PFMaBiSmAd.

The math makes much more sense now.

Thanks

Jonathan Smith

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Calculating Hours with a From and To Time?

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