Parse and create ISO 8601 Date and time intervals, like PT15M in PHP

Question

A library and webservice I am using communicates time-intervals in ISO 8601 format: PnYnMnDTnHnMnS. I want to convert such formats to seconds. And vice versa. Seconds are a

Answer 1

function parsePTTime($pt_time)
{
    $string = str_replace('PT', '', $pt_time);
    $string = str_replace('H', 'Hour', $string);
    $string = str_replace('M', 'Minute', $string);
    $string = str_replace('S', 'Second', $string);

    $startDateTime = '19700101UTC';
    $seconds = strtotime($startDateTime . '+' . $string) - strtotime($startDateTime);

    return $seconds;
}

Tests:

PT1H         - OK
PT23M        - OK
PT45S        - OK
PT1H23M      - OK
PT1H45S      - OK
PT23M45S     - OK
PT1H23M45S   - OK