Yes, but I made a small programm wich results in:

int Zahl = (54 & 63);
std::cout << Zahl;

63= 111111
54= 110110
so Zahl = 54
What is the sense behind that?

Because if you multiply the numbers, bit for bit, and write it out (0x0=0, 1x0=0, 0x1=0, 1x1=1), that is what you get.

Yes, but I made a small programm wich results in:

int Zahl = (54 & 63);
std::cout << Zahl;

63= 111111
54= 110110
so Zahl = 54
What is the sense behind that?

Because if you multiply the numbers, bit for bit, and write it out (0x0=0, 1x0=0, 0x1=0, 1x1=1), this is what you get.