time calculations

[raynestorm]

Hi--
I have been struggling to figure out how to handle time in php. I need to take two times that come from an input form and that are in the HH:MM am/pm style and subtract them to find out the difference in hours and minutes. I came up with this function, but it doesn't quite work. Does anybody know where I am going wrong? Does anybody know of a function that will handle time calculations? Thanks so much.
<?php
function timeDiff($timeIn, $timeOut)
{
$timeIn = explode(":",$timeIn);
$timeOut = explode(":",$timeOut);
$hours = $timeOut[0]-$timeIn[0];

if($timeOut[1]>=$timeIn[1]) $mins = $timeOut[1]-$timeIn[1];
else $mins = 60-($timeIn[1]-$timeOut[1]);
if(strlen($hours)==1) $hours="0".$hours;
if(strlen($mins)==1) $mins="0".$mins;
return $hours:$mins;

}
?>
--rayne

[saintp]

I'd convert them both to timestamps using mktime(), subtract, and then convert back to whatever format you want using the date() function. So:

function timeDiff($timeIn, $timeOut) { 
   list($hin, $min) = explode(":",$timeIn); 
   list($hout, $mout) = explode(":",$timeOut); 
   return date("H:i a", mktime($hin, $min) - mktime($hout, $mout));
}

That assumes that $timeIn > $timeOut, but you get the idea.

[drew010]

this code seems to work fine:

<?php 
echo timeDiff("3:30", "8:30");


function timeDiff($timeIn, $timeOut) 
{ 
$timeIn = explode(":",$timeIn); 
$timeOut = explode(":",$timeOut); 
$hours = $timeOut[0] - $timeIn[0]; 

if($timeOut[1] >= $timeIn[1]) {
	$minutes = $timeOut[1] - $timeIn[1];
} else {
	$minutes = $timeOut[1] - $timeIn[1] + 60;
	$hours--;
}

if(strlen($hours) == 1) {
	$hours = "0" . $hours;
}
if(strlen($minutes) == 1) {
	$minutes = "0" . $minutes;
}

return $hours . ":" . $minutes;

} 
?> 

[raynestorm]

Thanks for the reply. So, if I have:

<?php
function timeDiff($timeIn, $timeOut) {  

   list($hin, $min) = explode(":",$timeIn);  

   list($hout, $mout) = explode(":",$timeOut);  

   return date("H:i a", mktime($hin, $min) - mktime($hout, $mout)); 
}
?>
<?php
if ((isset($_POST["MM_insert"])) && ($_POST["MM_insert"] == "form1")) {
  $insertSQL = sprintf("INSERT INTO tutor_log (record_id, period, `date`, activity, student, teacher, timeIn, timeOut, timeTotal) VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s)",
                       GetSQLValueString($_POST['record_id'], "text"),
                       GetSQLValueString($_POST['period'], "text"),
                       GetSQLValueString($_POST['date'], "text"),
                       GetSQLValueString($_POST['activity'], "text"),
                       GetSQLValueString($_POST['student'], "text"),
                       GetSQLValueString($_POST['teacher'], "text"),
                       GetSQLValueString($_POST['timeIn'], "text"),
                       GetSQLValueString($_POST['timeOut'], "text"),
                       $timeTotal = timeDiff($timeIn, $timeOut)
);
?>

and I get this error message: You have an error in your SQL syntax near ':00 am)' at line 1. Here's what I am inserting:
My SQL Statement ($insertSQL): INSERT INTO tutor_log (record_id, period, date, activity, student, teacher, timeIn, timeOut, timeTotal) VALUES ('559', '12', '1076967295', NULL, NULL, NULL, '09:00am', '2:00pm', 01:00 am)

Where did I go wrong?
Thanks
--rayne

[raynestorm]

Drew010: Thanks, but that code doesn't handle something like this:
echo timeDiff("9:05am", "3:01pm");
My times must be in am/pm format
Thanks.
--rayne

[drew010]

edit
Try this then:

<?php  

echo timeDiff("3:30pm", "8:30pm"); 


function timeDiff($timeIn, $timeOut)  

{
$timeIn = explode(":",$timeIn);  

$timeOut = explode(":",$timeOut);  

if(strtolower(substr($timeIn[1], -2)) == "pm") {
    $timeIn[1] = substr($timeIn[1], 0, 2);
    $timeIn[0] += 12;
}

if(strtolower(substr($timeIn[1], -2)) == "am") {
    $timeIn[1] = substr($timeIn[1], 0, 2);
}

if(strtolower(substr($timeOut[1], -2)) == "pm") {
    $timeOut[1] = substr($timeOut[1], 0, 2);
    $timeOut[0] += 12;
}

if(strtolower(substr($timeOut[1], -2)) == "am") {
    $timeOut[1] = substr($timeOut[1], 0, 2);
}

$hours = $timeOut[0] - $timeIn[0];  

if($timeOut[1] >= $timeIn[1]) { 
    $minutes = $timeOut[1] - $timeIn[1]; 
} else { 
    $minutes = $timeOut[1] - $timeIn[1] + 60; 
    $hours--; 
} 

if(strlen($hours) == 1) { 
    $hours = "0" . $hours; 
} 
if(strlen($minutes) == 1) { 
    $minutes = "0" . $minutes; 
} 

return $hours . ":" . $minutes; 

}  

?> 

[raynestorm]

Thanks! That works, except I have to edit this line:

return $hours . ":" . $minutes;

to be:

return $hours, $minutes;

or I got an error message that I have an error in my sql.
--rayne