在g ++中使用std :: copysign

Question

I just figured out some incompatibilities between my tested platforms using std::copysign.

At a first test I try in MSVC to get some algorithms tested. Now I tried to port this c++(11) code to the Xilinx Zynq platform (A9+FPGA).

This is working so far except there is no std::copysign including cmath. So I have to use copysign without the namespace.

What would be the proper way of adding this function to the namespace?

PS: I do not want to manage the same files on different platforms by hand just for namespace incompatibilities.

Compile flag is:

-c -fmessage-length=0 -MT"$@" -mcpu=cortex-a9 -mfpu=vfpv3 -mfloat-abi=hard -std=c++11

Answer 1

You could create a macro for msvc.

#if defined(_MSC_VER) 
#define copysign std::copysign
#endif

However, c++11 should have the std namespace. If you aren't compiling with c++11 enabled you might be getting a older set of libraries maybe? I'd check to make sure that you are. If you can't compile with c++11 on your platform then the above should work. Add more preprocessor flags to target more platforms if needed.

Another option is

using namespace std;

which would cover both cases.