PHP Unconference Europe 2015

pow

(PHP 4, PHP 5)

powExponential expression

Descrierea

number pow ( number $base , number $exp )

Returns base raised to the power of exp.

Notă:

In PHP 5.6 onwards, you may prefer to use the ** operator.

Parametri

base

The base to use

exp

The exponent

Valorile întoarse

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

Exemple

Example #1 Some examples of pow()

<?php

var_dump
(pow(28)); // int(256)
echo pow(-120); // 1
echo pow(00); // 1

echo pow(-15.5); // PHP >4.0.6  NAN
echo pow(-15.5); // PHP <=4.0.6 1.#IND
?>

Note

Notă:

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

Vedeți de asemenea

  • 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 3 notes

up
17
chris at ocportal dot com
2 years ago
Many notations use "^" as a power operator, but in PHP (and other C-based languages) that is actually the XOR operator. You need to use this 'pow' function, there is no power operator.

i.e. 3^2 means "3 XOR 2" not "3 squared".

It is particular confusing as when doing Pythagoras theorem in a 'closet points' algorithm using "^" you get results that look vaguely correct but with an error.
up
7
scott at arciszewski dot me
8 months ago
As of PHP 5.6.0alpha2, there is now an exponentiation operator. If this is kept in the final release, it may be worth noting here.

<?php
// These two will be equivalent as of PHP 5.6.0
$x = $y ** 2;
$x = pow($y, 2);
?>
up
9
gilthansREMOVEME at gmail dot com
7 years ago
Note that pow(0, 0) equals to 1 although mathematically this is undefined.
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