Same line of code working in one visual studio project, but not in another

[rudiHammad]

Hello,
I came across this very strange problem. I have 2 visutal studio project, and in both of them I have in the header file this:

class GameScene: public cocos2d::Scene{
//...some code
private:
    boolean KEYS[255] = {false};
}

In one of the project everything workd perfectly, no errors. In the other one, literally the exact same line errors with this:

I have absolutly no idea what is going on. And being new to cpp, I am having trouble understanding the errors. What is really puzzling is that it only fails in one project. ¿¿??

thanks

[rudiHammad]

okey, I solved it…kind of.
Instead of “boolean”, I used “bool” in the second project and it worked. But why does “boolean” work in the other project?