PHP filesize() 函数是什么

PHP filesize() 函数是什么？相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。

                                                           filesize

作用：函数返回指定文件的大小

语法：

filesize(filename)

参数：

filename：必需。规定要检查的文件。

返回值：

返回文件大小的字节数，如果出错返回 FALSE 并生成一条 E_WARNING 级的错误。

filesize 示例

示例一

<?php

// 输出类似：somefile.txt: 1024 bytes

$filename = 'somefile.txt';
echo $filename . ': ' . filesize($filename) . ' bytes';

?>

示例二

<?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];
}
?>

示例三

<?php
/**
* Converts bytes into human readable file size.
*
* @param string $bytes
* @return string human readable file size (2,87 Мб)
* @author Mogilev Arseny
*/
function FileSizeConvert($bytes)
{
    $bytes = floatval($bytes);
        $arBytes = array(
            0 => array(
                "UNIT" => "TB",
                "VALUE" => pow(1024, 4)
            ),
            1 => array(
                "UNIT" => "GB",
                "VALUE" => pow(1024, 3)
            ),
            2 => array(
                "UNIT" => "MB",
                "VALUE" => pow(1024, 2)
            ),
            3 => array(
                "UNIT" => "KB",
                "VALUE" => 1024
            ),
            4 => array(
                "UNIT" => "B",
                "VALUE" => 1
            ),
        );

    foreach($arBytes as $arItem)
    {
        if($bytes >= $arItem["VALUE"])
        {
            $result = $bytes / $arItem["VALUE"];
            $result = str_replace(".", "," , strval(round($result, 2)))." ".$arItem["UNIT"];
            break;
        }
    }
    return $result;
}

?>

示例四

<?php
/**
* Return file size (even for file > 2 Gb)
* For file size over PHP_INT_MAX (2 147 483 647), PHP filesize function loops from -PHP_INT_MAX to PHP_INT_MAX.
*
* @param string $path Path of the file
* @return mixed File size or false if error
*/
function realFileSize($path)
{
    if (!file_exists($path))
        return false;

    $size = filesize($path);
   
    if (!($file = fopen($path, 'rb')))
        return false;
   
    if ($size >= 0)
    {//Check if it really is a small file (< 2 GB)
        if (fseek($file, 0, SEEK_END) === 0)
        {//It really is a small file
            fclose($file);
            return $size;
        }
    }
   
    //Quickly jump the first 2 GB with fseek. After that fseek is not working on 32 bit php (it uses int internally)
    $size = PHP_INT_MAX - 1;
    if (fseek($file, PHP_INT_MAX - 1) !== 0)
    {
        fclose($file);
        return false;
    }
   
    $length = 1024 * 1024;
    while (!feof($file))
    {//Read the file until end
        $read = fread($file, $length);
        $size = bcadd($size, $length);
    }
    $size = bcsub($size, $length);
    $size = bcadd($size, strlen($read));
   
    fclose($file);
    return $size;
}

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