问题
In my code (game engine code) there are multiple source (.c) files which maintain the status of the game, status like
START
CONFIGURE
STOP
END
DEFAULT
RUNNING
for maintaining state, one global variable gameStatus used which shared between multiple source files using extern keyword. now I have read that the global variable is bad to use and it allows the outside module to change it and as the number of components using global variable increases, the complexity of the interactions can also increase.
So I have limited scope that variable to one file using static keyword and added accessor methods like get or set APIs in the same file. So other files only access that variable using accessor APIs.
I have removed the global variable that is good but now every other file which used that global variable have to call accessor APIs which seems to add the overhead of function calls,
so now I am confused which is better? any C standard about how efficiently share the data between different source files?
回答1:
The fact that global variables are "bad practice" is entirely opinion based and 100% dependent on the context. It is impossible to say whether you are applying such "bad practice" or not without looking at your code. Global variables are not bad practice per se, using them in the wrong way is. Global variables are often necessary in C. Take as an example the C standard library: errno is a global variable that is used basically everywhere in both library code and user code to check for errors. Is that bad practice? Could they have defined a function get_errno() instead (well to be honest they actually did it's just hidden... but that's for complex concurrency reasons)? I'll let you decide.
In your specific case, changing a globally visible variable to static and then creating two functions only to get and set its value is totally unnecessary. Any part of the code can still modify the variable, but now it's just more annoying to do so, and it could also lead to slower code if not optimized correctly. All in all, by creating those functions you just stripped the variable of the static qualifier.
来源：https://stackoverflow.com/questions/61592399/do-i-really-needed-accessor-functions-to-access-global-variable-from-another-fil