C++ warning of data comparision

Question

I have one WORD variable in my program.

WORD hour;

But when I compare It

if(hour>=0 && hour<=18)
{
    hour+=6;
}

It will generate warning [Warning] comparison is always true due to limited range of data type

I am using Dev-C++ as IDE.

Answer 1

if(hour>=0 && hour<=18)

I think the warning is for the comparison hour >=0 which is always true for hour is of type WORD which is a typedef of unsigned short (usually) which means hour is always greater than or equal to 0:

 typedef unsigned short WORD;

On MSVC++ it is how WORD is defined, check your compiler if it is unsigned or not. If it unsigned¹, then hour >=0 is obviously true for all possible values of hour. In that case, you need to write just this:

if(hour<=18) //(hour >= 0) is implied by its type
{
    hour+=6;
}

^{1. Note that it doesn't matter whether is unsigned int or unsigned short. As long as it is unsigned, hour >=0 will be true for all possible values of hour.}