What is the reason for this strange floating point result

[maiyappan]

float a=9.9;
if(a<9.9) printf("true");
else printf("false") ;
ans:true how is it possible?

[Banfa]

Easy, floating point numbers are an approximation, approximations can change when operated on.

You have assigned the double constant (9.9)to a float variable so it has converted that double to float.

Then you compare the float variable to a double constant (9.9) so the compiler converts the variable from a float to a double.

So note that in the first 2 lines of your code the constant double 9.9 is implicitly cast down to a float and the implicitly cast back up to a double. With-in those casts it is perfectly with-in the relms of possibility that 9.9 becaomes 9.8999999999999 9 or less so true gets printed.

To avoid it either define a as a double or use floating point constants 9.9f to avoid implicit casts.

Try reading this too;

[maiyappan]

thank u banfa may i know u r name

[Banfa]

Sorry no; as a matter of personal security policy I don't give out personal information to the general public :-7