Cacher is the code snippet organizer for pro developers

<?php 

function timeAgoInWords($datetime, $now = null){
  if($now === null){ $now = date('Y-m-d H:i:s'); }

  $units = array(
    'y' => 31104000,
    'm' => 2592000,
    'd' => 86400,
    'h' => 3600,
    'i' => 60,
    's' => 1,
  );

  $words = array(
    'past'   => '前',
    'future' => '後',
    'y' => '年',
    'm' => 'ヶ月',
    'd' => '日',
    'h' => '時間',
    'i' => '分',
    's' => '秒',
  );

  $prefix   = '約';

  $time_ago = '';
  $sec      = strtotime($datetime);
  $now_sec  = strtotime($now);
  $diff_sec = $now_sec - $sec;

  $direction = $diff_sec > 0 ? $words['past'] : $words['future'];

  $decrease_sec = $diff_sec;
  $divides = array('y' => 0, 'm' => 0, 'd' => 0, 'h' => 0, 'i' => 0, 's' => 0);
  foreach($divides as $key => $val){
    $divides[$key] = (int)($decrease_sec / $units[$key]);
    $decrease_sec %= $units[$key];
  }

  $time_ago = '';
  $keys = array_keys($divides);
  foreach($keys as $key){
    if($divides[$key] > 0){ 
      $time_ago .= $divides[$key] . $words[$key]; 
    }
  }

  $time_ago = $prefix . $time_ago . $direction;
  return $time_ago;
}

echo timeAgoInWords(date('Y-m-d H:i:s', time() - 186400));