Convert a date format in PHP

Note: Because this post's answer sometimes gets upvoted, I came back
here to kindly ask people not to upvote it anymore. My answer is
ancient, not technically correct, and there are several better
approaches right here. I'm only keeping it here for historical
purposes.

Although the documentation poorly describes the strtotime function,
@rjmunro correctly addressed the issue in his comment: it's in ISO
format date "YYYY-MM-DD".

Also, even though my Date_Converter function might still work, I'd
like to warn that there may be imprecise statements below, so please
do disregard them.

The most voted answer is actually incorrect!

The PHP strtotime manual here states that "The function expects to be given a string containing an English date format". What it actually means is that it expects an American US date format, such as "m-d-Y" or "m/d/Y".

That means that a date provided as "Y-m-d" may get misinterpreted by strtotime. You should provide the date in the expected format.

I wrote a little function to return dates in several formats. Use and modify at will. If anyone does turn that into a class, I'd be glad if that would be shared.

function Date_Converter($date, $locale = "br") {
    # Exception
    if (is_null($date))
        $date = date("m/d/Y H:i:s");
    # Let's go ahead and get a string date in case we've
    # been given a Unix Time Stamp
    if ($locale == "unix")
        $date = date("m/d/Y H:i:s", $date);
    # Separate Date from Time
    $date = explode(" ", $date);
    if ($locale == "br") {
        # Separate d/m/Y from Date
        $date[0] = explode("/", $date[0]);
        # Rearrange Date into m/d/Y
        $date[0] = $date[0][1] . "/" . $date[0][0] . "/" . $date[0][2];
    }
    # Return date in all formats
        # US
        $Return["datetime"]["us"] = implode(" ", $date);
        $Return["date"]["us"]     = $date[0];
        # Universal
        $Return["time"]           = $date[1];
        $Return["unix_datetime"]  = strtotime($Return["datetime"]["us"]);
        $Return["unix_date"]      = strtotime($Return["date"]["us"]);
        $Return["getdate"]        = getdate($Return["unix_datetime"]);
        # BR
        $Return["datetime"]["br"] = date("d/m/Y H:i:s", $Return["unix_datetime"]);
        $Return["date"]["br"]     = date("d/m/Y", $Return["unix_date"]);
    # Return
    return $Return;
} # End Function