PHP 5.4.36 Released

gmp_strval

(PHP 4 >= 4.0.4, PHP 5)

gmp_strvalConvert GMP number to string

Beschreibung

string gmp_strval ( GMP $gmpnumber [, int $base = 10 ] )

Convert GMP number to string representation in base base. The default base is 10.

Parameter-Liste

gmpnumber

The GMP number that will be converted to a string.

Dies kann entweder eine resource für einen GMP-Wert in PHP 5.5 oder voher sein, ein GMP-Objekt in PHP 5.6 und später oder ein numerischer String, wenn es möglich ist, diesen in einen GMP-Wert umzuwandeln.

base

The base of the returned number. The default base is 10. Allowed values for the base are from 2 to 62 and -2 to -36.

Rückgabewerte

The number, as a string.

Changelog

Version Beschreibung
5.3.2 The base was extended from 2 to 36, to 2 to 62 and -2 to -36.

Anmerkungen

Hinweis:

To use the extended base introduced in PHP 5.3.2, then PHP must be compiled against GMP 4.2.0 or greater.

Beispiele

Beispiel #1 Converting a GMP number to a string

<?php
$a 
gmp_init("0x41682179fbf5");
printf("Decimal: %s, 36-based: %s"gmp_strval($a), gmp_strval($a,36));
?>

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User Contributed Notes 3 notes

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1
caldwell at utm dot NoSpamPlease dot edu
13 years ago
Warning: gmp_strval may return a null terminated string (e.g., gmp_strval(gmp_init(8)) has two characters. This is because gmp is built for speed, so uses estimates based on things it can get quickly, like the number of bits in N. So since 8 is a 4 bit number, it will be allocated ceil(log10(2^4))=ceil(4*0.30103....) = 2 characters. The gmp folks feel it is the caller's responsibility (in this case the PHP interface) to check whether or not all the characters were required.  PHP might have done this for us (and may in the future), but for now, you need to check (if it matters to you--it sure did in my program!).
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0
russell dot s dot harper at gmail dot com
4 years ago
A gotcha when using the value from gmp_strval as a key in an associative array. Some numbers are 2^31 are converted to signed integer format, this is usually incorrect.

<?php

$a
= gmp_init('2147483649'); // = 2^31 + 1
$b = gmp_init('3173604585'); // = 2^31 < $b < 2^32

$c = gmp_strval($a);
$d = gmp_strval($b);

$e = array($c => 'c', $d => 'd');

print
'*** Expect '."\n";
print
'Array '."\n".'('."\n".'    ['.$c.'] => c'."\n".'    ['.$d.'] => d'."\n".')'."\n\n";
print
'*** Actual '."\n";
print_r($e);

?>

Output:

*** Expect
Array
(
    [2147483649] => c
    [3173604585] => d
)

*** Actual
Array
(
    [-2147483647] => c
    [3173604585] => d
)

A workaround is to format as base 16 and append '0x' before using as a key.
up
0
php at richardneill dot org
8 years ago
I think it's no longer necessary to worry about trailing nulls. This was fixed in Feb 2002 (see bug 10133)
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