将字符串转换为数字并返回字符串？ [英] Convert a string to number and back to string?

问题描述

我想知道如何将一个简短的ASCII字符串转换成数字（int，float或numeric string）。我看到一些这里的帖子提到完美散列，看起来像可能是我需要的。但是，我不太了解这个数学。

I would like to know how I can convert a short ASCII string to a number (int, float, or numeric string). I saw a couple of posts here mentioned perfect hashes which seems like it might be what I need. However, I'm not quite understanding the math for this.

如何将ASCII字符串转换成数字序列，然后返回到字符串？

作为附注，将字符串拆分成ASCII字符数字很容易。

As a side note, breaking a string down into it's ASCII character numbers is easy enough.

foreach(str_split($string) as $char) $number .= ord($char);

更新

阅读更多后，我来了与此。不过，我想知道是否有缩短数字序列，所以不太长。

class intnum
{
    public static $charset = array(
        32 => ' ', 33 => '!', 34 => '"', 35 => '#', 36 => '$',
        37 => '%', 38 => '&', 39 => "'", 40 => '(', 41 => ')',
        42 => '*', 43 => '+', 44 => ',', 45 => '-', 46 => '.',
        47 => '/', 48 => '0', 49 => '1', 50 => '2', 51 => '3',
        52 => '4', 53 => '5', 54 => '6', 55 => '7', 56 => '8',
        57 => '9', 58 => ':', 59 => ';', 60 => '<', 61 => '=',
        62 => '>', 63 => '?', 64 => '@', 65 => 'A', 66 => 'B',
        67 => 'C', 68 => 'D', 69 => 'E', 70 => 'F', 71 => 'G',
        72 => 'H', 73 => 'I', 74 => 'J', 75 => 'K', 76 => 'L',
        77 => 'M', 78 => 'N', 79 => 'O', 80 => 'P', 81 => 'Q',
        82 => 'R', 83 => 'S', 84 => 'T', 85 => 'U', 86 => 'V',
        87 => 'W', 88 => 'X', 89 => 'Y', 90 => 'Z', 91 => '[',
        92 => '\\', 93 => ']', 94 => '^', 95 => '_', 96 => '`',
        97 => 'a', 98 => 'b', 99 => 'c', 100 => 'd', 101 => 'e',
        102 => 'f', 103 => 'g', 104 => 'h', 105 => 'i', 106 => 'j',
        107 => 'k', 108 => 'l', 109 => 'm', 110 => 'n', 111 => 'o',
        112 => 'p', 113 => 'q', 114 => 'r', 115 => 's', 116 => 't',
        117 => 'u', 118 => 'v', 119 => 'w', 120 => 'x', 121 => 'y',
        122 => 'z', 123 => '{', 124 => '|', 125 => '}'
    );

    public static function fromNumber($number)
    {
        $string = '';
        while($number)
        {
            $value = substr($number, 0, 2);
            $number = substr($number, 2);

            if($value < 32)
            {
                $value .= substr($number, 0, 1);
                $number = substr($number, 1);
            }

            $string .= self::$charset[ (int) $value];
        }
        return $string;
    }

    public static function fromString($string)
    {
        $number = '';
        foreach(str_split($string) as $char) $number .= ord($char);
        return $number;
    }
}

$string = 'this is my test string to convert';

$number = intnum::fromString($string);
$string = intnum::fromNumber($number);

推荐答案

一个字符串到数字编码器作为一行（PHP 5.3样式）：

A string-to-number encoder as one-liner (PHP 5.3 style):

$numbers = join(array_map(function ($n) { return sprintf('%03d', $n); },
                          unpack('C*', $str)));

它只是将每个字节转换为十进制数等效，将其零填充到固定长度3数字，所以它可以被明确地转换回来。

It simply converts every byte into its decimal number equivalent, zero-padding it to a fixed length of 3 digits so it can be unambiguously converted back.

解码器回到一个字符串：

The decoder back to a string:

$str = join(array_map('chr', str_split($numbers, 3)));

示例文本：

Wörkswíthallストリングズ

087195182114107115032119195173116104032097108108032227130185227131136227131170227131179227130176227130186

Wörks wíth all ストリングズ
087195182114107115032119195173116104032097108108032227130185227131136227131170227131179227130176227130186

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