# pow

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

powEspressione esponenziale

### Descrizione

pow(float `\$base`, float `\$esp`): float

Restituisce `base` elevato alla potenza di `esp`. Se possibile, questa funzione restituisce un integer.

Se la potenza non può essere computata, viene generato un errore, e pow() restituirà `false`. dalla versione 4.2.0 di PHP la funzione pow() non genera alcun warning.

Nota:

Il PHP non può gestire valori negativi per `base`s.

Example #1 Alcuni esempi di pow()

``` <?phpvar_dump( pow(2,8)); // int(256)echo pow(-1, 20); // 1echo pow(0, 0); // 1echo pow(-1, 5.5); // errore?> ```
Avviso

Nel PHP 4.0.6 e precedenti, pow() restituiva sempre un float e non generava alcun errore.

Vedere anche exp() sqrt() bcpow() e gmp_pow().

### User Contributed Notes 6 notes

42
chris at ocportal dot com
10 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. ```
Roman
1 year ago
``` If you use negative numbers, you need to use brackets for using with **<?php-1 ** 2; // -1(-1) ** 2; // 1?> ```
raiika
4 years ago
``` It is official now that you could use <?php2 ** 3; // 8// instead ofpow(2, 3); // 8?> ```
13
gilthansREMOVEME at gmail dot com
15 years ago
``` Note that pow(0, 0) equals to 1 although mathematically this is undefined. ```
scott at arciszewski dot me
8 years 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);?> ```
jaxx1rr at gmail dot com
3 years ago
``` funny thingnumber_format(pow(2, 1023));gives a long numberbut number_format(pow(2, 1024));gives inf ```