Compound condition in C: if (0.0 < a < 1.0)

Question

I recently noticed that the following expression compiles in my compiler (Clang):

float a;
if (0.0 < a < 1.0) { ... }

Does this do wh

Answer 1

Does this do what I expect?

No, it does

(0.0 < a) < 1.0

and (0.0 < a) yields 0 or 1. So you end up having 0 < 1.0 or 1 < 1.0 evaluated.

Note that in some other languages it does what you expect.

For example in Python,

a < b < c

is called a chained comparison and it is equivalent to:

(a < b) and (b < c)