Math 函数
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octdec

(PHP 4, PHP 5)

octdec — 八进制转换为十进制

说明

number octdec ( string $octal_string )

返回 octal_string 参数所表示的八进制数的十进制等值。可转换的最大的数值为 17777777777 或十进制的 2147483647。PHP 4.1.0 开始，该函数可以处理大数字，这种情况下，它会返回 float 类型。

Example #1 octdec() 范例

<?php
echo octdec('77') . "\n";
echo octdec(decoct(45));
?>

以上例程会输出：

63
45

参见 decoct()bindec()，hexdec() 和 base_convert().。

参数

octal_string

The octal string to convert

返回值

The decimal representation of octal_string

更新日志

版本 说明
Since 4.1.0 The function can now convert numbers that are too large to fit into the platforms integer type, larger values are returned as float in that case.

范例

Example #2 octdec() example

<?php
echo octdec('77') . "\n";
echo octdec(decoct(45));
?>

以上例程会输出：

63
45

参见

Math 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: 八进制转换为十进制

用户评论:

cubbo at quakenet dot php (18-Feb-2009 01:49)

Hi, this is an attempt to explain octdec().

There is one bug, if input is not octal, it doesn't return a proper decimal.

<?php

$octal = (int) "764";

function octal_to_decimal($int)
    {               
        $data = integer;
        $i = (strlen($int) - 1);   
        $parse_int = str_split($int);
        foreach($parse_int as $value)
            {
                $data += (int)($value * pow(8, $i));
                $i--;
            }       
        return $data;
    }
/**
*    explanation of the PHP function octdec()
*/
print octal_to_decimal($octal) . "<br />";

/**
*    the PHP function octdec()
*/
print octdec($octal);

?>

contato at andersonfraga dot net (18-Aug-2008 09:30)

Number is octal?

Simple and easy:

<?php

function is_octal($x) {
    return decoct(octdec($x)) == $x;
}

echo is_octal(077); // true
echo is_octal(195); // false

?>

Thanks
[]'s

harry at disgruntledgoat dot com (27-Mar-2007 11:03)

Calling the sticky bit "text" is not erroneous: On UNIX back in 1974, it instructed the operating system to retain the text segment of the program in swap space after the process exited. This speeded subsequent executions by allowing the kernel to make a single operation of moving the program from swap to real memory.

(11-Sep-2002 09:51)

The 'S' flag for Unix file access rights is badly computed in the above sample.
If the corresponding 'x' bit (exec) is not set, and the 's' bit (setgid/setuid/sticky) is set, then the flag should not be displayed as and uppercase 'S', but as a lower case 's'. Also the sticky bit (mainly used for folders with public right access rights such as /tmp to protect against deletion by non owner) is badly named ("text"?).

meheler at searchbc dot com (26-Oct-2001 04:03)

This function and decoct work great when working with file permissions. For example:

<?php
    $mode = octdec('4750');
   
    $user['suid']     = ($mode & 04000);
    $user['read']     = ($mode & 00400);
    $user['write']    = ($mode & 00200);
    $user['execute']  = ($mode & 00100);
   
    $group['sgid']    = ($mode & 02000);
    $group['read']    = ($mode & 00040);
    $group['write']   = ($mode & 00020);
    $group['execute'] = ($mode & 00010);
   
    $other['text']    = ($mode & 01000);
    $other['read']    = ($mode & 00004);
    $other['write']   = ($mode & 00002);
    $other['execute'] = ($mode & 00001);
   
    $attrs = array('-','-','-','-','-','-','-','-','-','-');
   
    if ($system['dir']) $attrs[0] = 'd';
   
    if ($user['read']) $attrs[1] = 'r';
    if ($user['write']) $attrs[2] = 'w';
    if ($user['execute']) $attrs[3] = 'x';
    if ($user['suid']) $attrs[3] = 'S';
   
    if ($group['read']) $attrs[4] = 'r';
    if ($group['write']) $attrs[5] = 'w';
    if ($group['execute']) $attrs[6] = 'x';
    if ($group['sgid']) $attrs[6] = 'S';

    if ($other['read']) $attrs[7] = 'r';
    if ($other['write']) $attrs[8] = 'w';
    if ($other['execute']) $attrs[9] = 'x';
    if ($other['text']) $attrs[9] = 'T';
   
    echo '<pre>';
    echo 'Mode Decimal: ' . $mode . "\n";
    echo 'Mode Octal: ' . decoct($mode) . "\n";
    echo 'Mode String: ' . implode('',$attrs)."\n";
    echo '</pre>';
?>

Outputs:

Mode Decimal: 2536
Mode Octal: 4750
Mode String: -rwSr-x---

-Mike