a = 9;(a=1001)
b = 11;
a=a^b; 1001(a)^1011(b)=0010
☟
b=a^b; 0010(a)^1011(b)=1001
☟
a=a^b; 0010(a) ^ 1001(b) = 1011
a = 11;
b = 9;