Question About Globals

[oompah62]

I have seen a few programs for unix that seem to group a lot of variables into a structure. They will init the variables somewhere near the beginning of the program and then pass a pointer to this structure in nearly every function call.

Why do they do this, instead of, ie.
declare "global_t foo" in main.c, malloc and init in main(),
and then declare "extern global_t foo" in every other file and skip passing the pointer completely?

BTW. I tested this both ways with LCC, and it made absolutely no difference in the size of the .exe. Did the compiler write exactly the same code both ways?

[Kinasz]

I think it is because when you are reading code and a bunch of variables are all part of a structure it is a bit easier to know what they are doing(in a large program) eg: cats.berman = 3 and cats.persion = 5 is easier to understand than berman = 3 and than persion = 5 appearing out of nowhere.

Dont hold me to that but thats how it was described to me.

[Kinasz]

I should add that when they are in a structure you can pass them in to functions as read only, so that function cant modify the values if youve made a mistake in your code. Its also easy to see in the function prototype whethor or not the function will modify any values or just read them.