Chaining of Relational operators is giving wrong output [closed]

Answer 1

This:

18.5<=bmi<23

means the same as

(18.5 <= bmi) < 23

In other words the value of bmi is never compared to 23. You must not use that kind of math-syntax in C, it should be written as:

(18.5 <= bmi) && (bmi < 23)

So it's really two comparisons of the variable, and must be written using the boolean-and (&&) operator to make this explicit.