GMP
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GMP 函数

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More mathematical functions can be found in the 数学扩展 section

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GMP
在线手册：中文 英文
PHP手册
PHP手册 - N: GMP 函数

用户评论:

Nitrogen (07-Sep-2010 04:02)

I made a function that can be used for converting numbers to any base you wish.. instead of returning a string of pre-defined index of characters (i.e. 0-9a-z) you could simply make your own of any length using the array of indexes it returns.
I looked around and didn't see anybody made one, I needed one for a simple compression algorithm with only numbers, I've not actually made it yet but this was an initial idea.

<?php
// ConvertBase function explained:
// we add an array item $Input%$Base floored and divide $Input by $Base floored.
// repeat until $Input is no longer above 0.

function ConvertBase($Input,$Base=10) {
  $Input=gmp_init($Input);
  $Result=array();

  for($i=0;$i<1||gmp_sign($Input)==1;$i++) {
    $Result[]=gmp_intval(gmp_mod($Input,$Base));
    $Input=gmp_div_q($Input,$Base);
  }
  $Result=array_reverse($Result);
  return($Result);
}

// an example how gmp_strval($.., 36); could be achieved:

// the funny emergency number from The IT Crowd
// (leading zeroes aren't liked in gmp_init though)
$Input = '1189998819991197253';

// our example 36 characters used in gmp_strval($.., 36);
$Chars = '0123456789abcdefghijklmnopqrstuvwxyz';

// count the $Chars so they're all used
// or use your own number less than the length of $Chars
$Base = strlen($Chars);

// perform
$Result = ConvertBase($Input,$Base);

// replace the resulting index with the corrosponding characters of the index in $Chars
for($i=0;$i<count($Result);$i++)
  $Result[$i]=$Chars{$Result[$i]};

// compare
printf("gmp_strval:  %s\r\n",gmp_strval($Input,36));
printf("BaseConvert: %s\r\n",implode($Result));

/* OUTPUT:
gmp_strval:  91h7dixfq6h1
BaseConvert: 91h7dixfq6h1
*/
?>
The example shows a familiar result of course, but the idea of this function was so that you can use whatever base you wish, and display entirely your own output to represent any number of choice.

Also, for those who wish to do bitwise shifting, it's quite simple.. to shift left, just multiply the number by pow(2,x), and to shift right, divide by pow(2,x).

<?php
function gmp_shiftl($x,$n) { // shift left
  return(gmp_mul($x,gmp_pow(2,$n)));
}

function gmp_shiftr($x,$n) { // shift right
  return(gmp_div($x,gmp_pow(2,$n)));
}
?>

Have fun,
Nitrogen.

john at worldmapad dot com (23-Jul-2006 07:24)

Here's a quick and dirty way to use simple GMP functions with PHP without recompiling. It is dependent upon the use of the exec() function, so make sure you can use exec(). While in safe mode you must consider the safe_mode_exec_dir directive. And don't simply pass user input to the exec function without validating the input first!

Download and Install GMP as instructed in README and INSTALL files.
On my MAC OS X Server, I just did the following:
./configure
make
make check
make install
This installed it in the /usr/local directory. There were some errors, but not with any functions I needed.
Within the gmp-4.#.# cd into the demos directory. Then compile pexpr.c by typing:
make pexpr
This is a simple expressions parser which serves as a simple interface to some of the basic GMP functions.
You can test it then like:
./pexpr "102394874783 * 23498748";
Now you may interface with it using PHP's exec() function.

richard-slater.co.uk (22-Feb-2004 09:03)

For those (like me) who are trying to do bit masking with very large numbers, here is a useful function to do the work for you.

<?php
  function isBitSet($bitMask, $bitMap)
  {
    return (bool) gmp_intval(gmp_div(gmp_and($bitMask, $bitMap),$bitMask));
  }
?>

helvecio_oliveira at yahoo dot com dot br (15-Oct-2003 09:51)

=============================================================
A set of very nice functions to handle IP Address with gmplib:

The best way to store a range into a database is store:
dNet ..... decimal representation of a Net
dMask .... decimal representation of a Mask

All another parameters can be calculated.

<?
/*
f_ip2dec($a) ................... IP string to decimal
f_dec2ip($a) ................... decimal to IP string

f_dec2ipall($dNet,$dMask) ...... decimal Net and Mask to an Array with several IP parameters

f_dec2cidr($a) ................. decimal Mask to CIDR

f_and($a,$b) ................... and
f_or($a,$b) .................... or
f_xor($a,$b) ................... xor
f_not($a) ...................... not
f_dec2bin($a) .................. decimal to binary string
f_bin2dec($a) .................. binary string to decimal
*/

function f_and($a,$b){
$a=gmp_init(strval($a));
$b=gmp_init(strval($b));
$d=gmp_and($a,$b);
return floatval(gmp_strval($d));
}

function f_or($a,$b){
$a=gmp_init(strval($a));
$b=gmp_init(strval($b));
$d=gmp_or($a,$b);
return floatval(gmp_strval($d));
}

function f_xor($a,$b){
$a=gmp_init(strval($a));
$b=gmp_init(strval($b));
$d=gmp_xor($a,$b);
return floatval(gmp_strval($d));
}

function f_not($a){
$a=gmp_init(strval($a));
$d=gmp_strval($a,2);
$d=str_replace("1","x",$d);
$d=str_replace("0","1",$d);
$d=str_replace("x","0",$d);
$d=gmp_init($d,2);
return floatval(gmp_strval($d,10));
}

function f_dec2bin($a){
$a=gmp_init(strval($a));
return gmp_strval($a,2);
}

function f_bin2dec($a){
$a=gmp_init(strval($a),2);
return floatval(gmp_strval($a,10));
}

function f_ip2dec($a){
$d = 0.0;
$b = explode(".", $a,4);
for ($i = 0; $i < 4; $i++) {
        $d *= 256.0;
        $d += $b[$i];
    };
return $d;
}

function f_dec2ip($a){
    $b=array(0,0,0,0);
    $c = 16777216.0;
    $a += 0.0;
    for ($i = 0; $i < 4; $i++) {
        $k = (int) ($a / $c);
        $a -= $c * $k;
        $b[$i]= $k;
        $c /=256.0;
    };
    $d=join('.', $b);
    return($d);
}

function f_dec2cidr($a){
$a=gmp_init(strval($a));
$d=strlen(str_replace("0","",gmp_strval($a,2)));
return $d;
}

function f_dec2ipall($dNet,$dMask){
  $dWildCard=f_not($dMask);
  $IpAll["Net"]=f_dec2ip($dNet);
  $IpAll["Mask"]=f_dec2ip($dMask);
  $IpAll["WildCard"]=f_dec2ip($dWildCard);
  $IpAll["Cidr"]=f_dec2cidr($dMask);
  $IpAll["Bcast"]=f_dec2ip(f_or($dNet,$dWildCard));
  $IpAll["nIp"]=$dWildCard+1;
  $IpAll["nIpUtil"]=$dWildCard-1;
  if($IpAll["nIp"] > 2){
        $IpAll["IpFrom"]=f_dec2ip($dNet+1);
        $IpAll["IpTo"]=f_dec2ip($dNet+$dWildCard-1);
  }
  else
  {
        $IpAll["IpFrom"]="-";
        $IpAll["IpTo"]="-";
        $IpAll["nIpUtil"]=0;
  }
  return $IpAll;
}

?>

=============================================================
GMP install steps in Mandrake 9.1:
----------------------------------------------------------
cp -r /usr/src/php-devel/extensions/gmp /tmp/gmp
cd /tmp/gmp
phpize
./configure
make install
echo "extension = gmp.so" > /etc/php/90_gmp.ini

Restart apache web server.
----------------------------------------------------------
gmp.so is in:
/usr/lib/php/extensions/

look in phpinfo, the string:
/etc/php/90_gmp.ini

Needs these tools:
autoconf
automake
libtool
m4
php430-devel-430-11mdk.rpm
all rpms that are envolved to run and compile gmp (*gmp*.rpm)

Some docs about self contained extensions:
/usr/share/doc/php430-devel-430/SELF-CONTAINED-EXTENSIONS
=============================================================