how cout<<"0x7b = "<<0x7b<<endl; produces output: 0x7b = 123

Question

also
cout<<"0x123 = " << 0x123 << endl;
output:
0x123 = 291
Now I'm learning number system such as binary, unary, hexadecimal.
I read forums. But I can't understand this. Please help me!

Answer 1

123 in hex: 3*16^0 + 2*16 + 16^2 = 3 + 32 + 256 = 291 in decimal

Answer 2

0x7b is hexadecimal, and its decimal form is 123, not 291.

Answer 3

it's all still the same statement for the output.