PHP 7.0.6 Released

    gmp_nextprime

    (PHP 5 >= 5.2.0, PHP 7)

    gmp_nextprime — Find next prime number

    Description

    GMP gmp_nextprime ( int $a )

    Find next prime number

    Parameters

    a

    Either a GMP number resource in PHP 5.5 and earlier, a GMP object in PHP 5.6 and later, or a numeric string provided that it is possible to convert the latter to a number.

    Return Values

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

    Examples

    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";
    ?>

    The above example will output:

    11
-997

    Notes

    Note:

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

    User Contributed Notes

    Anonymous
    2 months ago
    It seems gmp_nextprime on negative numbers always returns 2.
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