Question

Is there any inbuilt function in c++ or c libraries that can be used to find distance between two points in 2-D space

PS: I know how to implement it myself.

Answer 1

Well, you can use arithmetic on complex numbers:

using point_t = std::complex<int>;

double distance(point_t a, point_t b) {
    return std::abs(b - a);
}

I realise that this doesn’t quite fulfil your requirement of not writing your own function but the actual distance logic is implemented in the std::norm function. It just returns the square of the distance.