If an arithmetic operation that yields a floating point type produces a value that is not in the range of representable values of the result type, the behavior is undefined according to the C++ standard, but may be defined by other standards the machine might conform to, such as IEEE 754.

float x = 1.0;
for (int i = 0; i < 10000; i++) {
    x *= 10.0; // will probably overflow eventually; undefined behavior
}