下面是一个使用log10的选项:

<?php

function format_number(float $d): string {
   $e = (int)(log10($d) / 3);
   return sprintf('%.3f', $d / 1e3 ** $e) . ['', ' k', ' M', ' G'][$e];
}

$s = format_number(9012345678);
var_dump($s == '9.012 G');

https://php.net/function.log10

极其简单的函数来获取人类文件大小。

原始来源:http://php.net/manual/de/function.filesize.php#106569

复制/粘贴代码:

<?php
function human_filesize($bytes, $decimals = 2) {
  $sz = 'BKMGTP';
  $factor = floor((strlen($bytes) - 1) / 3);
  return sprintf("%.{$decimals}f", $bytes / pow(1024, $factor)) . @$sz[$factor];
}
?>

灵活的解决方案:

function size($size, array $options=null) {

    $o = [
        'binary' => false,
        'decimalPlaces' => 2,
        'decimalSeparator' => '.',
        'thausandsSeparator' => '',
        'maxThreshold' => false, // or thresholds key
        'suffix' => [
            'thresholds' => ['', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y'],
            'decimal' => ' {threshold}B',
            'binary' => ' {threshold}iB',
            'bytes' => ' B'
        ]
    ];

    if ($options !== null)
        $o = array_replace_recursive($o, $options);

    $base = $o['binary'] ? 1024 : 1000;
    $exp = $size ? floor(log($size) / log($base)) : 0;

    if (($o['maxThreshold'] !== false) &&
        ($o['maxThreshold'] < $exp)
    )
        $exp = $o['maxThreshold'];

    return !$exp
        ? (round($size) . $o['suffix']['bytes'])
        : (
            number_format(
                $size / pow($base, $exp),
                $o['decimalPlaces'],
                $o['decimalSeparator'],
                $o['thausandsSeparator']
            ) .
            str_replace(
                '{threshold}',
                $o['suffix']['thresholds'][$exp],
                $o['suffix'][$o['binary'] ? 'binary' : 'decimal']
            )
        );
}

var_dump(size(disk_free_space('/')));
// string(8) "14.63 GB"
var_dump(size(disk_free_space('/'), ['binary' => true]));
// string(9) "13.63 GiB"
var_dump(size(disk_free_space('/'), ['maxThreshold' => 2]));
// string(11) "14631.90 MB"
var_dump(size(disk_free_space('/'), ['binary' => true, 'maxThreshold' => 2]));
// string(12) "13954.07 MiB"

这是我的选择，简短明了:

/**
 * @param int $bytes Number of bytes (eg. 25907)
 * @param int $precision [optional] Number of digits after the decimal point (eg. 1)
 * @return string Value converted with unit (eg. 25.3KB)
 */
function formatBytes($bytes, $precision = 2) {
    $unit = ["B", "KB", "MB", "GB"];
    $exp = floor(log($bytes, 1024)) | 0;
    return round($bytes / (pow(1024, $exp)), $precision).$unit[$exp];
}

或者，更愚蠢和有效:

function formatBytes($bytes, $precision = 2) {
    if ($bytes > pow(1024,3)) return round($bytes / pow(1024,3), $precision)."GB";
    else if ($bytes > pow(1024,2)) return round($bytes / pow(1024,2), $precision)."MB";
    else if ($bytes > 1024) return round($bytes / 1024, $precision)."KB";
    else return ($bytes)."B";
}

伪代码:

$base = log($size) / log(1024);
$suffix = array("", "k", "M", "G", "T")[floor($base)];
return pow(1024, $base - floor($base)) . $suffix;

我的方法

    function file_format_size($bytes, $decimals = 2) {
  $unit_list = array('B', 'KB', 'MB', 'GB', 'PB');

  if ($bytes == 0) {
    return $bytes . ' ' . $unit_list[0];
  }

  $unit_count = count($unit_list);
  for ($i = $unit_count - 1; $i >= 0; $i--) {
    $power = $i * 10;
    if (($bytes >> $power) >= 1)
      return round($bytes / (1 << $power), $decimals) . ' ' . $unit_list[$i];
  }
}