base_convert()

(PHP 4, PHP 5, PHP 7)

在任意进制之间转换数字

说明

返回一字符串，包含$number以$tobase进制的表示。$number本身的进制由$frombase指定。$frombase和$tobase都只能在 2 和 36 之间（包括 2 和 36）。高于十进制的数字用字母 a-z 表示，例如 a 表示 10，b 表示 11 以及 z 表示 35。

由于使用内部的"double"或"float"类型，base_convert()的操作可能会导致大数值中的精度丢失。请参见本手册的浮点数章节以便获得更多详细信息。

参数

要转换的数字

The base$numberis in

The base to convert$numberto

返回值

$numberconverted to base$tobase

范例

Example #1base_convert()例子

以上例程会输出：

101000110111001100110100

参见

• intval() 获取变量的整数值

Convert an arbitrarily large number from any base to any base.
string convBase(string $numberInput, string $fromBaseInput, string $toBaseInput)
$numberInput number to convert as a string
$fromBaseInput base of the number to convert as a string
$toBaseInput base the number should be converted to as a string
examples for $fromBaseInput and $toBaseInput
'0123456789ABCDEF' for Hexadecimal (Base16)
'0123456789' for Decimal (Base10)
'01234567' for Octal (Base8)
'01' for Binary (Base2) 
You can really put in whatever you want and the first character is the 0.
Examples:

Typical use-cases:
1. Convert a large arbitrary precision number to base-36.
2. Convert a 32-char hexadecimal UUID (128-bit) to a 25-char base-36 unique key, and vice versa.
Examples:

ABCDEF00001234567890 (hexadecimal) = 3o47re02jzqisvio (base-36) 
ABCDEF01234567890123456789ABCDEF (hexadecimal) = a65xa07491kf5zyfpvbo76g33 (base-36)

If you need to use base_convert with numbers larger then 32 bit, the following gmp implementation of base_convert should work. 

If you would like to convert numbers into just the uppercase alphabet base and vice-versa (e.g. the column names in a Microsoft Windows Excel sheet..A-Z, AA-ZZ, AAA-ZZZ, ...), the following functions will do this.

Microsoft Windows Excel stops at IV (255), but this function can handle much larger. However, English words will start to form after a while and some may be offensive, so be careful.

a binary coded decimal is converted by taking groups of four from a decimal string,
for example the binary coded decimal string
1000 = 8
10001000 does not = 136 but 88
so
binarycodedstring2dec(1000) = 8
binarycodedstring2dec(11100000111001)=3839
binarycodedstring2dec(100000111001)=839
i truly have no idea if this function will be useful to anyone, i simply failed a physics midterm because i didn't know this so i wrote this function to make sure i would never forget how to convert binary coded decimals

Base62x gives an alternative way for traditional Base62 and/or Base64.
base62x_encode / base62x_decode would be merged into PHP as an extra module in the future.
Prior to that, users can download the PHP extra module via: https://github.com/wadelau/Base62x

A RFC 4648 Compliant Base32 encode. Send me an email if you end up making this thing more efficient with bitwise operations and whatever else. 

Really huge numbers might be truncated at both ends.
eg:

will output:
9E8EA23CB63C0000000000000000000000000000000000000000000000000000 (64 hex digits)
when the correct result would be:
6A9E8EA23CB63C228F31AD9268B4097F156D6AA11DCB29F14BACCFF196CE3F0AD2 (66 hex digits)
Notice that as well as the result showing '0's after B63C which you would expect it is also missing the first 6A before 9E.

While not immediately clear from the description above, a negative sign is also "silently ignored".
base_convert("-12", 10, 10)  =>  12

Note that the method can only convert max 1024 long numbers. Most people don't nee that but once I ran into an issue where binary string was converted into alphanumeric. In such case, you need to split them, convert them and join.

I wrote this as part of a college assignment to shorten urls. It works for any base and with any range of characters, eg. A-Za-z0-9 etc. Hope it helps someone. 

In order to convert base 26 (hexavigesimal) of just alphanumeric characters (A-Z), wthout integers, (as descibed at http://en.wikipedia.org/wiki/Hexavigesimal), I found this to be useful:
function base_convert_alpha( $str, $from, $to )
{
  $r = range( 'A', 'Z' );
  $clean = str_replace( $r, array_keys($r), $str );
  return base_convert( $clean, $from, $to );
}
echo base_convert_alpha( "BAC", 26, 10 );
//$clean = 102 which then returns 678

output: string(3) "314"

Convert any length bits to HEX:
function bits2hex($bin)
{
  $out = "";
  for($i=0;$i 65)   $partialCode = creaSpeedCode($resultINT,$partialCode,$BASECODE);
  return $BASECODE[$resultINT].$partialCode;
}
echo $speedCodeDEC."
";
echo $risultato = creaSpeedCode ( $speedCodeDEC,"",$BASECODE);

[EDIT BY danbrown AT php DOT net: This function provides conversion of Arabic numerals (those used by most of the world, the standard 1,2,3,4,...) into Roman numerals (I,II,III,IV,...). The original author failed to provide a description, but due to the usefulness of the function, it is being preserved from deletion, and a simple description added.] 

Extending base_convert to bases above 36, up to base 62.

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