Forward declaring a typedef of an unnamed struct

Question

Possible Duplicate:
Forward declarations of unnamed struct

If I have

typedef struct tagPAGERANGE
{
    int iFirstPage;
    int iLastPage;
} PAGERANGE;

I can forward declare it that way

struct tagPAGERANGE;
typedef struct tagPAGERANGE PAGERANGE;

But what I have is

typedef struct
{
    int iFirstPage;
    int iLastPage;
} PAGERANGE;

I'm not sure how I can do it. I only want to hold a pointer to this struct. Right now I'm stuck with either including a rather substantial header, or duplicating the definition of the struct.

Doesn't look much like C++. Why did you tag it with "C++" tag? — Griwes, Apr 20 '12 at 16:03
C and C++ are different languages. Which language are you asking about? — Robᵩ, Apr 20 '12 at 16:06
@Griwes The project it comes from is a C++ project. It compiles in C++. — sashoalm, Apr 20 '12 at 16:09
@Robᵩ I'll remove any of the 2 tags, just choose one. My project is a C++ project, so I'll remove the C tag. — sashoalm, Apr 20 '12 at 16:12
Who the heck voted to close as not a real question? Just because the answer is "it's not possible" it doesn't make it any less valid. — R. Martinho Fernandes, Apr 20 '12 at 16:13
@mydogisbox I actually searched for 3-4 minutes before asking the quesiton but couldn't find anything unnamed structs. Maybe I wasn't using the best search terms. But I really am not willing to search for 1 hour before gathering courage to ask a question. — sashoalm, Apr 20 '12 at 16:19
@satuon Nothing wrong with posting a dup. It just gets closed. — N_A, Apr 20 '12 at 16:24
@satuon, I meant that `typedef struct XXX {...} YYY;` is de facto C; in C++, you would just do `struct YYY {};` and be done with it. So there is really no place for "C++" tag here. — Griwes, Apr 21 '12 at 16:22
the question is how to get the c++ compiler to accept this. coding style aside. — aepurniet, Mar 08 '16 at 00:35

Cat Plus Plus · Accepted Answer · 2012-04-20T16:11:59.627

13

It's impossible. You can only declare named structs.

Think about what identifies a struct that doesn't have a name, and how do you tell the compiler that it's that struct you want. If it doesn't have a name, it's identified by its members, so you need to provide members — i.e. define it. Therefore, you can't just declare it — you don't have a luxury of an identifier other than the definition itself.

edited Apr 20 '12 at 16:11

answered Apr 20 '12 at 16:02

Cat Plus Plus

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there is a workaround: http://stackoverflow.com/a/7304634/347508 – kritzikratzi Apr 07 '16 at 00:24

score 2 · Answer 2 · answered Apr 20 '12 at 16:15

2

Since this is used in a C++ code, just get rid of the typedefs altogether, they are unnecessary and bad style in C++.

The real solution is to just use named structs:

struct foo; // forward declaration

struct foo {
    // … implementation
};

The typedefs are not useful.

answered Apr 20 '12 at 16:15

Konrad Rudolph

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The header file that uses those typedefs is not mine, and it's designed to work in both C and C++. – sashoalm Apr 20 '12 at 16:17
@satuon In that case see the duplicate question. As the cat said, this is simply not possible but the other question shows a (hideous) workaround. – Konrad Rudolph Apr 20 '12 at 16:18

Forward declaring a typedef of an unnamed struct

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