How to turn off all layers except the specified layer

[LeeJaeYoung]

I want to learn how to turn off everything except the specified layer.
However, I followed the site below, but not all layers are turned off.

API hide all layers - Graphisoft Community

This site asks questions about changing the above code to version 27.
I found out that the index code only works within the number of layers.

Solved: Re: attrib.header.index = i; is error. - Graphisoft Community

I know how to know the number, but
I don't know what the first index is and what the next index is.
Where should I study?

[DGSketcher]

You know this ability is available in the Quick Layers palette ? 

I can't help you on the API, but thought I would mention it in case you missed the existing tool.

[LeeJaeYoung]

thank you This is a question I asked to create an environment while working.
Yes, I am using the quick layer you mentioned well.

I'm asking because there are times when I need to turn on a few disabled layers and turn off all layers while working.
Thank you again for your interest.
Have a nice day.

[LeeJaeYoung]

What I want to know is that I can find out the number with getnum. Then how can I get the indices in order?
Is there no way?

[LeeJaeYoung]

If you know what the maximum value of the layer index is,
It's okay to search by index from 0 to the maximum value, but is there a function that can find the maximum and minimum values?

[Viktor Kovacs]

I think this answer might help you as well:

https://community.graphisoft.com/t5/Archicad-C-API/How-can-I-hide-or-show-layers-by-name/m-p/581361/...