CakeFest 2017 NYC, the Official CakePHP Conference

gmp_nextprime

(PHP 5 >= 5.2.0, PHP 7)

gmp_nextprimeFind next prime number

Descrierea

GMP gmp_nextprime ( int $a )

Find next prime number

Parametri

a

Un număr GMP sub formă de resource în PHP 5.5 și anterior, un obiect GMP în PHP 5.6 și ultrior, su un șir de caractere numeric atunci când acesta poate fi convertit într-un număr.

Valorile întoarse

Return the next prime number greater than a, as a GMP number.

Exemple

Example #1 gmp_nextprime() example

<?php
$prime1 
gmp_nextprime(10); // next prime number greater than 10
$prime2 gmp_nextprime(-1000); // next prime number greater than -1000

echo gmp_strval($prime1) . "\n";
echo 
gmp_strval($prime2) . "\n";
?>

Exemplul de mai sus va afișa:

11
-997

Note

Notă:

This function uses a probabilistic algorithm to identify primes and chances to get a composite number are extremely small.

add a note add a note

User Contributed Notes 3 notes

up
1
Anonymous
1 year ago
It seems gmp_nextprime on negative numbers always returns 2.
up
0
IceMetalPunk at gmail dot com
22 days ago
Negative numbers N always have at least four factors: N*1=N and abs(N)*-1=N. Therefore, even if "natural number" weren't in the definition of a prime (which it is), no negative number would ever qualify. Therefore, the next-largest prime number to any negative number is always 2.
up
0
Tommy Lynge Jrgensen
8 months ago
Prime numbers are positive, non-zero numbers that have exactly two factors. No more, no less. So testing negative numbers doesn't really make any sense.
To Top