Convert string to number and back to string?

Question

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 messages here , mentioning perfect hashes that seem to him maybe what I need . However, I do not quite understand the math for this.

How can you convert an ASCII string to a sequence of numbers and then return to the string?

As a side note, breaking a string into it with ASCII character numbers is quite simple.

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

Update

After more reading, I came up with this. However, I am wondering if there is a shorten the numerical sequence , so it does not take so long.

 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); 

Answer 1

A line-to-number encoder as a single-line (PHP 5.3 style):

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

It simply converts each byte to its decimal number, equivalent to zero, filling it up to a fixed length of three digits so that it can be unambiguously converted back.

The decoder returns to the line:

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

Sample text:

Wörks all all ス ト リ ン グ ズ
087195182114107115032119195173116104032097108108032227130185227131136227131170227131179227130176227130186

Answer 2

You cannot just enter ORD characters in a string of numbers and expect it to return, because some characters may be 2 characters and others 3.

For instance:

Kang-HO will give you: 10797106103457279

Now, how do you know this: 10-79-71-0-61-0-34-57-27-9?

You need to either fill all your numbers with three codes, and get: 107097106103045072079 and then break it into blocks of 3 numbers, and then ASC them back ...

Answer 3

Well, if you want to convert your string to a sequence of integers , you should always use a fixed block of numbers. In this case, 3, since ASCII uses 8-bit words, so the maximum possible integer is 2 ^ 8-1 = 255.

You must fill in unused space 0:

 function zero_fill($num){ if($num <= 9) $num = "00".$num; elseif($num <= 99) $num = "0".$num; return $num; } 

You can use the function you created in combination with this and restore the string, take a block of 3 integers and convert them back to the corresponding ASCII character.

 foreach(str_split($numberSeq, 3) as $asciiIntValue) $stringBack .= chr($asciiIntValue);