Subtracting dates with PHP

Absolut9

I searched for an answer to this, but the maojrity of them involved using MySQL and DATEDIFF().

I am trying to do the following. I have timestamped a text file that I have created with PHP. When a user visits, I need to check that timestamp and compare it to the current time. If the timestamp reads more than an hour ago, I want to be able to update the file again and put the updated timestamp back on it.

Is there a way to do with with PHP? Can Ijust subtract 2 dates like that and get a number that I can do something with?

Will subtracting
June 9 2005 7:29:05 from June 9 2005 08:30:31 give me something I can use to determine how much time has passed?

Thanks in advance!

vaaaska

convert both to a timestamp...get the difference...and then output from there...

timestamp()

drew010

you should take the timestamp of the file and subtract it from time(). if its greater than 3600 than its over an hour old and should be updated.
if you have date strings, they should be converted to a timestamp first using [man]strtotime[/man]. in php you cant do date arithmetic using string dates.

Absolut9

Soo...

I should create the timestamp on the file by doing:

echo time()

Then... when the script is run, run it again.

Then compare the timestamp of the file, with the current timestamp. If the difference between the 2 timestamps is greater than 3600, more than an hour has passed?

I think I've got it...

drew010


if (time() - filemtime("filename.txt") > 3600) {
  //older than 1 hour
} else {
  //newer than 1 hour
}

yeah its as simple as that.

Absolut9

Looks like I got it.. code for those that would like it. This takes data from a remote file, parses it into XML and then saves it locally. When the script it run, it checkes the file timestamp and updates it if more than an hour has passed.

if (file_exists($LocalFilename)) {
	// The file exists, Let's load the data.
		$Contents = ImportXMLDataFile($LocalFilename);
		$DateTimeNow = now();
		If (($DateTimeNow - $Contents[0]) >= 3600) {
		// An hour has passed, recreate the data file.
			$LocalFilename = CreateXMLDataFile($today, $showtype);
			$Contents = ImportXMLDataFile($LocalFilename);
	}
	else {
	// The file has not been created yet, create the file then import the data.
		$showtype = "All";
		$LocalFilename = CreateXMLDataFile($today2, $showtype);
		$Contents = ImportXMLDataFile($LocalFilename);
}
}