JavaScript Match on Binary bits - Case statement will not work

Off-Topic
1

"Off Topic" as this seems to be a JavaScript problem
I am expecting only the first case statement to be hit in the code below.
But all of them are hit.
Why?
I know there are no break statements that is on purpose.
I want code to be run if the relevant bit is set.
In the example below only bit 1 is set.
If the variable is, say 3, (Binary 0011) then I want the fist 2 case statements to hit.
Etc.

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image965×979 45.3 KB

function OnClick(clickData)
{
	// --------------------------------------------------------
	DOpus.ClearOutput();
	// --------------------------------------------------------
	var FeatureMask = 0x1;
	DOpus.Output("000-010 FeatureMask START            :" + ZeroPad(FeatureMask.toString(2),4));
	DOpus.Output("")


        switch(FeatureMask)
        {
            case (FeatureMask&0x1):
                DOpus.Output("     004000-200-000  Case FeatureMask&0x1    ---C =  " + ZeroPad(FeatureMask&0x1.toString(2),4));
                DOpus.Output("     004000-200-000  Case FeatureMask        ---C =  " + ZeroPad(FeatureMask.toString(2),4));
                DOpus.Output("");
            case (FeatureMask&0x2):
                DOpus.Output("     004000-220-000  Case FeatureMask&0x2    --B- =  " + ZeroPad(FeatureMask&0x2.toString(2),4));
                DOpus.Output("     004000-220-000  Case FeatureMask        --B- =  " + ZeroPad(FeatureMask.toString(2),4));
                DOpus.Output("");
            case (FeatureMask&0x4):
                DOpus.Output("     004000-240-000  Case FeatureMask&0x4    -A-- =  " + ZeroPad(FeatureMask&0x4.toString(2),4));
                DOpus.Output("     004000-240-000  Case FeatureMask        -A-- =  " + ZeroPad(FeatureMask.toString(2),4));
                DOpus.Output("");
            case (FeatureMask&0x8):
                DOpus.Output("     004000-280-000  Case FeatureMask&0x8    F--- =  " + ZeroPad(FeatureMask&0x8.toString(2),4));
                DOpus.Output("     004000-280-000  Case FeatureMask        F--- =  " + ZeroPad(FeatureMask.toString(2),4));
                DOpus.Output("");
            default:
                DOpus.Output("     004000-400-010  FeatureMask Default          =  " + ZeroPad(FeatureMask.toString(2),4));
        }
	// --------------------------------------------------------
}

function ZeroPad(s,c)
{
	s = s + "";
	while(s.length < c)
	{
		s = "0" + s;
	}
	return s;
}

In this example below

1 Like
2

Case statements according to ChatGPT will not do it.
It suggested the if construct below.
The explanation was flawed but good enough that I could work out that it was never going to work.
Fun claim - according to this guy for the last several years the about of compute expended or made available on AI ahs increased by a factor of 10.
So over 5 years that would be 10x10x10x10x10=100000 time capacity.
A sort of new Moore's Law and it is continuing.

I am starting to get real sue from ChatGTP to troubleshoot bits of my code....
Full ChatGTP output below from anyone interested.....

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image1070×7664 541 KB

3

Your original code is missing all the breaks at the end of each case.

It’s often better to look up how things work than ask ChatGPT to guess. :slight_smile:

4

Thanks @Leo
ChatGPT will only help real dumb programmers I think - like me :slight_smile:

5

It's been some days, but next time, you could do it like this? o)

if (FeatureMask & 1) { // first bit
    //..
}
if (FeatureMask & 2) { // 2nd
    //..
}
if (FeatureMask & 4) { // 3rd
    //..
}
if (FeatureMask & 8) { // 4th
    //..
}
if (FeatureMask & 16) { // 5th
    //..
}

If you want only one condition to be met at a time:

if (0);
else if (FeatureMask & 1) { // first bit
    //..
}
else if (FeatureMask & 2) { // 2nd
    //..
}
else if (FeatureMask & 4) { // 3rd
    //..
}
else if (FeatureMask & 8) { // 4th
    //..
}
else if (FeatureMask & 16) { // 5th
    //..
}
1 Like