Question

I’ve come across a bit of code which essentially looks like this:

#include<iostream>

// in a header file
class xxx{
  public:
    xxx() { xxx_[0]=0; xxx_[1]=0; xxx_[2]=0;}
    double x0() const {return xxx_[0];}
  private:
    double xxx_[3];  // ???
};

// in the main.cpp
int main(){
  xxx x;
  std::cout<<x.x0()<<"\n";
}

The question is — is declaring as a class member an array of fixed size is really allowed by the standard?

Answer 1

There is nothing wrong with the above code. It might not be the best way to write it, but there is nothing intrinsically wrong with it.

Yes, your class xxx may contain a fixed-size array as a member. It’s allowed in C too.

The compiler, even when reading the header to use it, knows how big to make sizeof(xxx) as a result.