PHPで西暦から元号に変換する関数

なんか、探すより作った方が早そうだったので。

<?php
function y2gengo($year)
{
    $year = intval($year);
    $str = $gengo = $y ="";
    
    if ( 1869 <= $year && $year < 1912){
        $gengo = "明治";
        $y     = $year - 1869 + 1;
        if ($year == 1869){
            $str   = "元";
        }
    }
    else if ( 1912 <= $year && $year < 1926){
        $gengo = "大正";
        $y     = $year - 1912 + 1;
        if ($year == 1912){
            $str   = "元";
        }
    }
    else if ( 1926 <= $year && $year < 1989){
        $gengo = "昭和";
        $y     = $year - 1926 + 1;
        if ($year == 1926){
            $str   = "元";
        }
    }
    else if ( 1989 <= $year ){
        $gengo = "平成";
        $y     = $year - 1989 + 1;
        if ($year == 1989){
            $str   = "元";
        }
    }
    
    
    if (!$str){
        $str = sprintf('%s%s', $gengo , strval($y));
    }
    
    
    return array(
        'gengo' => $gengo,
        'str'   => $str,
        'year'  => $y,
        );
}




    /// 元号をYYYYにする
    /**
     * @param String 元号(M/T/S/H)
     * @param int 年
     */
    function gengo2y($year, $gengo = 'H')
    {
        $gengo = substr(strtoupper($gengo), 0, 1);
        switch ($gengo){
          case 'M':
            $plus = 1868;
            break;
          case 'T':
            $plus = 1911;
            break;
          case 'S':
            $plus = 1925;
            break;
          case 'H':
          default:
            $plus = 1988;
            break;
        }
        
        return $year + $plus;
    }