Thread: difference between static int a and int static a?

hi all,
what is the difference between static int a and int static a?
thanks

Originally Posted by matsp

Whilst style dictates that you should use "static int", it's (apparently) valid to type "int static" - at least "gcc -Wall" doesn't complain about it. And from looking at the code, it does what you expect. I guess it's the same as "const int" or "int const".

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Mats

But not to be confused with: const int* vs. int* const which are quite different.

Originally Posted by cpjust

But not to be confused with: const int* vs. int* const which are quite different.

That's because the '*' is a different kind of entity. "static" and "int" are a storage class specifier and a type specifier, respectively. They bind to the declared entity. Whereas '*' is an actual part of the declared entity.

In fact, the fragments "const int*" and "int* const" are essentially meaningless because the name the star binds to has been left out. Think of it this way:

Code:

int *x;

This is not saying "x is a pointer to int." What it's really saying is, "*x is an int." Which of course implies that x itself must be a pointer to int. The star cannot be separated from the name. This is why I prefer the practice of attaching the star directly to the variable name instead of leaving a space. The star is NOT a type modifier.

Originally Posted by brewbuck

Code:

int *x;

This is not saying "x is a pointer to int." What it's really saying is, "*x is an int." Which of course implies that x itself must be a pointer to int. The star cannot be separated from the name. This is why I prefer the practice of attaching the star directly to the variable name instead of leaving a space. The star is NOT a type modifier.

Excuse me for asking, but how is there any difference between those two interpretations?

Originally Posted by robwhit

Excuse me for asking, but how is there any difference between those two interpretations?

Expanding on what dwks said already... Consider:

Code:

int *x, y;

This is, conceptually, declaring two integers: *x and y. If *x is an int, then x must be pointer to int. What it is NOT doing is declaring both to be pointer to int. It is easier to understand WHY it is this way if you think of it in the way I've outlined here.

Writing the star directly next to the type can trigger the misconception that the star is binding to the type specifier and therefore affecting each declarator in the declaration. But the reality is it binds to the DECLARATOR, not the type specifier, and so it only affects the declarator directly to its right.

Writing the star directly adjacent to the declarator makes it more clear that it does in fact bind rightward, not leftward.

Oh, I see. I thought you were saying something that referred to a statement with only one declarator.

Thanks.

Originally Posted by Elysia

My philosophy is that int* is a pointer-type variable pointing to it, so I always place them next to the type, (int* is a type, just like int!) and I never ever do int* n, n2 - when there's a pointer declaration, I always place it on a row of its own. Avoids confusion.

Me too.

Originally Posted by Elysia

My philosophy is that int* is a pointer-type variable pointing to int, so I always place them next to the type, (int* is a type, just like int!)

If int* was a type, then the following declaration would declare two int pointers:

Code:

int* x, y;

Except that it doesn't. Which proves that "int*" is not a type. Philosophies notwithstanding, the grammar is perfectly clear on this point.