asking for a code explanation

halo,

this is the line code


#define _CONCAT(a,b) a##b

the one in red colour is the operator i dont understand.

what does it mean?

Did you try looking it up in your C documentation?

Try this as a place to start... C preprocessor - Wikipedia, the free encyclopedia

Basically it does what it says it does, it concatenates two values.

If you wrote
int _CONCAT(myvar,123);

The compiler will see
int myvar123;

hey, thank you.