PHPKonf: Istanbul PHP Conference 2017


(PHP 4, PHP 5)

powExponential expression


number pow ( number $base , number $exp )

Returns base raised to the power of exp.


In PHP 4.0.6 and earlier pow() always returned a float, and did not issue warnings.



The base to use


The exponent

Return Values

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.


Version Description
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.


Example #1 Some examples of pow()


(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

See Also

  • exp() - Calculates the exponent of e
  • sqrt() - ریشه مربعی
  • bcpow() - عددی با دقت دلخواه به توان عدد دیگر
  • gmp_pow() - Raise number into power

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User Contributed Notes 3 notes

chris at ocportal dot com
4 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.
gilthansREMOVEME at gmail dot com
10 years ago
Note that pow(0, 0) equals to 1 although mathematically this is undefined.
scott at arciszewski dot me
2 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.

// These two will be equivalent as of PHP 5.6.0
$x = $y ** 2;
$x = pow($y, 2);
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