Question

it is known that operator [] is not concurrently safe for writing:
concurrent_vector::operator[] Operator
But what if I guarantee that different threads will write to different vector positions.
Like this (very much simplified example):

concurrent_vector<double> vec;
vec.resize(100);

parallel_for(0, 100, [&] (double ind)
{
    vec[ind] = ind*ind;
}

Is it concurrently safe or not? And if ‘not’ then why?

Thanks

Answer 1

Yes, it is concurrently safe as it’s like if you are accessing different variables.

As ildjam pointed out in the comment that would be safe even with regular std::vector or, let me add, with simple arrays.