Human readable times in PHP

time.php

# Set a timestamp to time, e.g. 2 months
public static function time_ago($timestamp)
{
    $years = floor($timestamp / 31536000);
    $days = floor(($timestamp - ($years*31536000)) / 86400);
    $hours = floor(($timestamp - ($years*31536000 + $days*86400)) / 3600);
    $minutes = floor(($timestamp - ($years*31536000 + $days*86400 + $hours*3600)) / 60);
    $timestring = '';
    if ($years > 0){
        $timestring .= $years . ' years ';
    }
    if ($days > 0) {
        $timestring .= $days . ' days ';
    }
    if ($hours > 0) {
        $timestring .= $hours . ' hrs';
    }
    if ($minutes > 0) {
        $timestring .= $minutes . ' mins';
    }
    
    # Optional
    # $timestring .= ' ago';

    return $timestring;
}

# Formats a time stamp into a date string
public static function format_timestamp($timestamp, $time = false)
{
    if($timestamp == 0) {
        return null;
    } else if(is_string($timestamp)){
        $timestamp = strtotime($timestamp);
    }
    if ($time) {
        $date_string = Date('H:i:s jS M Y', $timestamp);
    } else {
        $date_string = Date('jS M Y', $timestamp);
    }
    return $date_string;
}