PHP 度量前缀

/**
 * 数字转度量
 *
 * @param int $num 数字
 * @param int $precision 小数位数
 * @return string|int
 */
function num2metric($num, $precision = 0) {
    $unitList = [
        'P' => 15,
        'T' => 12,
        'G' => 9,
        'M' => 6,
        'W' => 4,
        'K' => 3,
    ];

    $num = (int) $num;

    foreach($unitList as $name => $pow) {
        $size = pow(10, $pow);

        if($num >= $size) {
            return bcdiv($num, $size, $precision) . $name;
        }
    }

    return $num;
}

num2metric(1000) // 1K
num2metric('10000') // 1W
num2metric('A') // 0