main() { float me = 1.1; double you = 1.1; if(me==you) printf("yes"); else printf("No"); }

For floating point numbers (float, double, long double) the values cannot be predicted exactly. Depending on the number of bytes, the precession with of the value represented varies. Float takes 4 bytes and long double takes 10 bytes. So float stores 0.9 with less precision than long double.