pow

    (PHP 4, PHP 5, PHP 7, PHP 8)

    pow — Exponential expression

    Description

    pow(mixed $num, mixed $exponent): int|float|object

    Returns num raised to the power of exponent.

    Note:

    It is possible to use the ** operator instead.

    Parameters

    num

    The base to use

    exponent

    The exponent

    Return Values

    num raised to the power of exponent. If both arguments are non-negative integers and the result can be represented as an integer, the result will be returned with int type, otherwise it will be returned as a float.

    PHP-Extensions may override the behaviour of this operation and make it return an object.

    Changelog

    Version Description
    8.4.0 Raising 0 to a negative exponent is now deprecated.

    Examples

    Example #1 Some examples of pow()

    <?php

    var_dump    (pow(2, 8)); / int(256)
    echo pow(-1, 20), PHP_EOL; / 1
    echo pow(0, 0), PHP_EOL; / 1
    echo pow(10, -1), PHP_EOL; / 0.1

    echo pow(-1, 5.5), PHP_EOL; / NAN
    ?>

    Example #2 Examples of pow() With GMP Extension Object

    <?php
    var_dump    (pow(new GMP("3"), new GMP("2"))); / object(GMP)
    ?>

    Notes

    Note:

    This function will convert all input to a number, even non-scalar values, which could lead to weird results.

    See Also

    • Exponentiation operator **
    • fpow() - Raise one number to the power of another, according to IEEE 754
    • exp() - Calculates the exponent of e
    • sqrt() - Square root
    • bcpow() - Raise an arbitrary precision number to another
    • gmp_pow() - Raise number into power

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    User Contributed Notes 2 notes

    up
    18
    gilthansREMOVEME at gmail dot com
    18 years ago
    Note that pow(0, 0) equals to 1 although mathematically this is undefined.
    up
    2
    Roman
    4 years ago
    If you use negative numbers, you need to use brackets for using with **

    <?php

    -1 ** 2; / -1

    (-1) ** 2; / 1

    ?>
    ＋add a note
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