c++ - What does this warning "pointer to a function used in arithmetic" mean?

Question

This question already has answers here: question from:https://stackoverflow.com/questions/65650463/what-does-this-warning-pointer-to-a-function-used-in-arithmetic-mean

Answer 1

This declaration:

static std::vector<int> race(int v1, int v2, int v3);

declares race to be a static member function that takes 3 int parameters and returns a std::vector<int>.

When you write race[0] the function race decays to a function pointer, and then you're indexing into that. The compiler is warning you that this never makes sense, which is true.

Note that you're only getting a warning instead of an error because you're presumably compiling the code with GCC, which accepts this code as an extension. As far as the language is concerned, this is not allowed, and is an error.

Also, the compiler is not referring to v1, v2, and v3 as functions, it's only referring to race as a function, which is also true.