gmp_init

(PHP 4 >= 4.0.4, PHP 5)

gmp_init — Crea un numero GMP

Descrizione

resource gmp_init ( mixed $number )

Crea un numero GMP partendo da un intero o da una stringa. La stringa può essere decimale o esadecimale. Nell'ultimo caso, la stringa dovrebbe iniziare con 0x.

Example #1 Creare un numero GMP


<?php
    $a = gmp_init (123456);
    $b = gmp_init ("0xFFFFDEBACDFEDF7200");
?>

Nota: Non è necessario chiamare uesta funzione se si vogliono usare interi o stringhe al posto di numeri GMP nelle funzioni GMP, come gmp_add(). Se se questa conversione è possibile e necessaria, gli argomenti delle funzioni vengono automaticamente convertiti in numeri GMP, usando le stesse regole di gmp_init().

gmp_intval

gmp_hamdist

Last updated: Fri, 18 Jul 2008

add a note User Contributed Notes
gmp_init

charlie at oblivion dot cz
18-Feb-2007 04:55


gmp_* functions don't accept strings with a leading '+':

<?php

echo gmp_strval(gmp_init('+42'));      #0

echo gmp_strval(gmp_add('42', '+42')); #42

echo bcadd('+42', '+42');              #84

?>

php at richardneill dot org
20-Sep-2006 03:30


Here's a way to parse a decimal (eg 3.25) into an integer and exponent:



<?

if (preg_match("/^[0-9]+\.[0-9]+$/",$input)){ 

     //Input is a base-10 decimal. Multiply as necessary to remove the decimal

     //point. Convert that to a gmp_resource, then decrement the exponent 

     //to compensate.



     $pieces=explode(".", $input);     //Split at the d.p.

     $input="$pieces[0]$pieces[1]";  //Remove the decimal point.



     $input=ltrim($input,'0');    

     //Remove any leading zeros, or gmp_init will parse the number as octal.



     if ($input==''){    //Deal with "0.0" which would otherwise be ''.

          $input=0;

      }

      $integer=gmp_init($input);   

      $ns_exponent=-strlen($pieces[1]);  

     //exponent = (-)  the number of characters after the decimal point.

}

?>

php at richardneill dot org
20-Sep-2006 03:14


Note: Leading zeros will make gmp_init parse this as octal.

Thus gmp_init(010) becomes 8.  



$a=010;              //8

$b="010" + 0;     //10

$c=gmp_strval(gmp_init(010));    //8

$d=gmp_strval(gmp_init("010")); //8



This behaviour is inconsistent: either $d should equal $b, or

$b should equal $a.

thomas dot hebinck at digionline dot de
18-Aug-2005 10:23


If you call a gmp_* function directly with an interger as parameter, this integer MUST NOT be 0:



for($i=-1;$i<=1;$i++) {  echo gmp_strval(gmp_add(2,gmp_mul(1,$i))) . ' ';  }



The result is 1 0 3 (wrong)



In this case you have to use gmp_init():



for($i=-1;$i<=1;$i++) {  echo gmp_strval(gmp_add(2,gmp_mul(1,gmp_init($i)))) . ' ';  }



The result is 1 2 3 (right)



Happy number crunching! :-)

add a note

gmp_intval

gmp_hamdist

Last updated: Fri, 18 Jul 2008