Question

I need to check a variable vi_theIndex for its value. At the given moment it has a value of 65.

I want to check if vi_theIndex is bigger or equal to zero AND smaller than 32.
Right now I do it like this:

long long vi_theIndex = 65;
if ((vi_theIndex >= 0) && (vi_theIndex < 32) )
 {
   //Case true
 }
else
{
   //Case false
}

I realized that the results are wrong for 65. The second case should come up but the first case becomes true. Why is this?

I tried this:

long long vi_theIndex = 65;

bool limitFlag1, limitFlag2;

limitFlag1 = (vi_theIndex <= 0);
limitFlag2 = (vi_theIndex = 65);

limitFlag2 becomes true and limitFlag1 becomes undefined, the debugger doesn´t even stop there on my breakpoint. It looks like C doesn´t understand the ‘<‘, ‘<=’ or ‘>’ signs. This also happens when I use the ‘<‘ or ‘>’ sign alone like here:

limitFlag1 = (vi_theIndex < 0);

limitFlag1 is not defined.

Can somebody please shed some light on this?

Answer 1

You must not be showing your real code for your first example – as you say, “case false” should be executed.

Your second example has a problem – you have vi_theIndex = 65, rather than vi_theIndex == 65, which you probably meant. The statement as you have it is always true. limitFlag1 will be 0 – I’m not sure what you mean by it “becomes undefined” – are you not showing your real code here, too?