which file define the PI value

hi , all
i need use PI in program, but i can't get PI value,,,which file define it , thanks...

I think it's in math.h. The name is M_PI.

thanks very much

If there is no such constant in math.h, try this:

Code:

---

#include <math.h>

double pi = atan(1.0) * 4.0;

---

I'm not sure if PI is standard in C inside of the math.h file, but it's certainly in there on good ol' linux gcc:

Code:

---

./math.h:# define M_PI          3.14159265358979323846  /* pi */

---