pi

Examples

The area of a circle with radius 2:

<?php
 
echo round(pi() * 2 ** 2, 2);

Output:

12.57

The M_PI constant holds the same value:

<?php
 
var_dump(pi() === M_PI);

Output:

bool(true)

Notes

Expressions usually use the M_PI constant — it is shorter and needs no function call.