ConFoo Montreal 2017 Calling for Papers

# pi

(PHP 4, PHP 5, PHP 7)

piGet value of pi

### Description

float pi ( void )

Returns an approximation of pi. The returned float has a precision based on the precision directive in php.ini, which defaults to 14. Also, you can use the `M_PI` constant which yields identical results to pi().

### Return Values

The value of pi as float.

### Examples

Example #1 pi() example

``` <?phpecho pi(); // 3.1415926535898echo M_PI; // 3.1415926535898?> ```

``` Pi is often usefull in con/sin/tan functions.. There are also other Pi related constants. These are most of them: M_PI  = 3.14159265358979323846 // pi // The following were added in PHP 4.0.0 M_PI_2 = 1.57079632679489661923 // pi/2 M_PI_4 = 0.78539816339744830962 // pi/4 M_1_PI = 0.31830988618379067154 // 1/pi M_2_PI = 0.63661977236758134308 // 2/pi M_SQRTPI = 1.77245385090551602729 // sqrt(pi) (Only in PHP 4.0.2+) M_2_SQRTPI = 1.12837916709551257390 // 2/sqrt(pi) ```
``` You can print pi in a more complicating way. In the code bellow we save pi as a variable and print its first 4 digits.\$n = pi();echo round (\$n,4); ```