Why pass a pointer to a global structure?

Question

This is going to probably be a stupid question but I am reviewing some code and I just don't see the point in what this guy is doing. In one C file he has defined a global structure that has many elements of many types. So from function "A" there is a call to function "B". In the call they are passing a pointer to the global structure and then in function "B" some stuff is done and part of the global is updated. Now This all seems like superfluous overkill since it is already a global. If the structure was local to function "A" I could totally see passing in the address to the structure into function "B". However the memory is permanently allocated already at the very top of the C file. In fact I can argue that there is a potential problem for someone else coming in a changing something and not realizing they have created a bug.

So I am sure there is a "good coding practice" BKM or something like that for doing this but I just can't see it. So in short, why create an address pointer and pass that to a function unnecessarily when the variable is already a global?

Answer 1

Passing the pointer is good style, primarily because globals are bad style. Perhaps the original developer is thinking about the possibility that the global may not be global, or the function that accepts it might possibly operate on a different variable (which may or may not also be global, but still needs to be identified).