Does C++ Recognize Pi

Mathematical ExpressionC++ SymbolDecimal RepresentationpiM_PI3.14159265358979323846pi/2M_PI_21.57079632679489661923pi/4M_PI_40.785398163397448309616

What does M_PI mean?

M_PI is defined as a macro #define M_PI 3.14159265358979323846264338327950288. in math. h and part of the POSIX standard. The values are identical, but you should use M_PI for portability reasons. (And for Swift, see How to get mathemical PI constant in Swift.)

What C++ library has PI?

The PI constant is present in the cmath header file. The name of the constant is M_PI. We can simply include that header file, and use the constant to perform operation.