SymfonyWorld Online 2022 Winter Edition

# pow

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

pow指数表达式

### 说明

pow(number `\$base`, number `\$exp`): number

`base`

The base to use

`exp`

### 返回值

`base``exp` 次方的幂。 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.

### 更新日志

4.2.0 如果不能计算幂，将发出一条警告，pow() 将返回 `false`pow() 开始不产生任何的警告。
4.0.6 如果可能函数现在会返回 integer 的结果，之前 总是返回 float，For older versions, you may receive a bogus result for complex numbers.

### 范例

``` <?phpvar_dump(pow(2, 8)); // int(256)echo pow(-1, 20); // 1echo pow(0, 0); // 1echo pow(-1, 5.5); // PHP >4.0.6  NANecho pow(-1, 5.5); // PHP <=4.0.6 1.#IND?> ```

### User Contributed Notes 6 notes

44
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. ```
16
raiika
3 years ago
``` It is official now that you could use <?php2 ** 3; // 8// instead ofpow(2, 3); // 8?> ```
12
gilthansREMOVEME at gmail dot com
15 years ago
``` Note that pow(0, 0) equals to 1 although mathematically this is undefined. ```
Roman
1 year ago
``` If you use negative numbers, you need to use brackets for using with **<?php-1 ** 2; // -1(-1) ** 2; // 1?> ```
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);?> ```
-3
jaxx1rr at gmail dot com
2 years ago
``` funny thingnumber_format(pow(2, 1023));gives a long numberbut number_format(pow(2, 1024));gives inf ```