pow
(PHP 4, PHP 5)
pow — Exponential expression
說明
number pow
( number $base
, number $exp
)
Returns base raised to the power of exp .
Warning
In PHP 4.0.6 and earlier pow() always returned a float, and did not issue warnings.
參數
- base
-
The base to use
- exp
-
The exponent
Return值
base raised to the power of exp . If the result can be represented as integer it will be returned as type integer, else it will be returned as type float. If the power cannot be computed FALSE will be returned instead.
更新日誌
| 版本 | 說明 |
|---|---|
| Since 4.0.6 | The function will now return integer results if possible, before this it always returned a float result. For older versions, you may receive a bogus result for complex numbers. |
| Since 4.2.0 | PHP stops to emit a warning if the value can't be computed, it will now silently return FALSE only. |
範例
Example#1 Some examples of pow()
<?php
var_dump(pow(2, 8)); // int(256)
echo pow(-1, 20); // 1
echo pow(0, 0); // 1
echo pow(-1, 5.5); // PHP >4.0.6 NAN
echo pow(-1, 5.5); // PHP <=4.0.6 1.#IND
?>