Float doesn't change when i add 0.1 to it

Question

I am quite a newbie to c. So when i writing a small game demo, i face a really strange problem.

 void testC()
 {
     float a = 825300160;
     float b = a +         


        

Answer 1

As this site shows, both a and b would be represented as

0 10011100 10001001100010001010011

in the IEEE standard for floats, where the first bit is the sign, the next 8 are the exponent, and the remaining 23 the mantissa. There's just not enough space in those 23 bits to represent the difference, because the exponent is so large.