comparing dates

[AdRock]

I have a form where i have 4 fields

 

1 for the start month and 1 for the start year

1 for the end month and 1 for the end year

 

I am trying to validate it so the the end month/year can't be before the start month/year

 

I have all the other form validation working but need some advice how i can do this last bit

 

Do I have to convert these form values into a date format for comparison and if so, how?

[BlueSkyIS]

one way:

 

$start_time = mktime(0,0,0,$start_month, 1, $start_year);
$end_time = mktime(0,0,0,$end_month,1, $end_year);

if ($end_time < $start_time) {
    die("end time is before start time");
}

[Fadion]

An identical approach, but using strtotime():

 

<?php
$startTime = strtotime($_POST['startyear'] . - . $_POST['startmonth']);
$endTime = strtotime($_POST['endyear'] . - . $_POST['endmonth']);
if($endTime < $startTime){
     echo 'End time should be less then start time.';
} else{
     //other code
}
?>