Why does C++ rand() seem to generate only numbers of the same order of magnitude?

Question

In a small application written in C/C++, I am facing a problem with the rand function and maybe the seed :

I want to produce a sequence of random numbers th

Answer 1

The lighter green is the region between 0 and 2²⁵; the darker green is the region between 2²⁵ and 2³⁰. The ticks are powers of 2.