Float Switch

Question

I`m trying to use switch with float to compact a code but I can`t. Can someone explain if it was supposed to be this and explain why? Thanks.

Answer 1

C++ requires a switch to be of an integral type. e.g. char, short, int, long long.

A float/double is a floating point so it's not accepted.

A floating point is imprecise, for example 5.3f * 1.2f should be 6.36f. Yet 5.3f * 1.2f == 6.36f is false.

A switch is converted to a binary search in assembly, or a lookup table ( an array ) depending on the cases.

A lookup table cannot use floats as indexes
A binary search requires a comparison using a subtraction.
2.33f - 0.33f, for example, is not equal to 2.f according to C++,
so it cannot compare either.

This is also the reason compilers warn you about floating comparisons.

Answer 2

You can not switch on a variable of type float. It is technically impossible for floats, because these numbers are not exact, whereas switch has the notion of exactly matching n different cases.

https://stackoverflow.com/questions/7856136/java-inaccuracy-using-double

Answer 3

Sorry for the time I took to come back here but thank you both. :D