Question

I have defined a function not in class

#define BlendLight(b1, b2)  std::max(b1, b2)

then in the class I am trying to use it:

float someFunk(float x, float y)
{
 return BlendLight(x,y); //Error here - BlendLight marked red (
}

And I get Error: Expected an identifier

I am try to compile this in Visual Studio 2010
std::max() header is included / I have add algorithm but error still present (((

Answer 1

The code isn’t erroneous as it stands. Most likely you have forgotten to

#include <algorithm>

This is the header file where std::max is defined.

Another possibility is that you didn’t define BlendLight in the same file as the class where you want to use it. In that case you have to #include the header file where BlendLight is defined.

Apart from this, you should know that what you have defined is not a function, but a preprocessor macro. In C++, you should rather use a proper (maybe inline) function for this task, so that your compiler can do type checking:

#include <algorithm>
// ...
template <class T>
T BlendLight(T x, T y)
{
  return std::max(x, y);
}