PHP Functions Essential Reference

pi

float pi(void) 

Returns the value of pi.

Returns:

Value of pi

Description:

Returns a double containing the value of pi. The number of decimal places is system-specific; for instance, on a Linux x86 box the value returned is 3.1415926535898.

Note that it will be slightly faster in most cases to simply use the named constant M_PI, which is provided by PHP. The pi() function simply returns this value.

Version:

PHP 3, PHP 4

Example:

Get pi

$radius = 6; $area = pi() * pow($radius, 2); // area = pi * r^2 echo "Area of circle with radius $radius is $area";