Why does decreasing the ASCII code by 32 translate into upper case not all Russian letters?

Question

C++ / C#

cout << (char) (((int) ch) - 32) << endl;
Works for A, but doesn't work for F anymore. Why?

Answer 1

That's why.

for(int i = 128; i < 256; ++i)
cout << i << " : "<< static_cast<unsigned char>(i) << endl;