Trying to use complex.h classes, some keyword is hiding it

I'm trying to implement a calculation which involves a sqare root and therefore has the possibility of becoming a complex number. I found that C++ has a standard complex number class which would work rather well, with multiplication and all. The only problem is somehow another keyword called complex is hiding the implementation, even when I try to use "std::complex" it says this error.

Code:

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error: `complex' undeclared (first use this function)
error: (Each undeclared identifier is reported only once for each function it appears in.)
error: expected `;' before "a"

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Anyone know how I can solve this?

May you post the interesting part of your code?

never mind, I thought it was an updated C library, but it uses standard templates. I just needed to give it a template argument.

By the way, remember that the header is <complex>, not <complex.h>.

yeah.

Man I didn't even know some of these classes existed.