error C2027 ?

zon_cpp

Hi! i define two structs in .h file:

struct s1
{
CString str;
struct s2* ss2;
};
struct s2
{
int i;
CString name;
};

and in .cpp file, in a function i use of this structs:

s1 myS;
myS.str = "";
myS.ss2->i = 0; // error C2027: use of undefined type s2

please help me, how do i solve this error?

Zo.Naderi-Iran

_Superman_

Put struct s2 before struct s1,

struct s2
{
int i;
CString name;
};

struct s1
{
CString str;
struct s2* ss2;
};

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Polymorphism in C

zon_cpp

ohhhhhhhh, my problem was solved; the problem is in struct name. the struct name was incorrect in my code.

struct s1
{
CString str;
struct z2* ss2; // the correct struct name is s2
};
struct s2
{
int i;
CString name;
};

and the error was : error C2027: use of undefined type z2 when i Write in code project, this code, i Pay attention this problem. thank you and excuse me,

Zo.Naderi-Iran

Peter_in_2780

«_Superman_» wrote:

Put struct s2 before struct s1,

This won't make any difference.

Software rusts. Simon Stephenson, ca 1994.

Lost User

Peter_in_2780 wrote:

This won't make any difference.

Try it.

It's time for a new signature.

ThatsAlok

SuperMan is right, there are two way to solve above problem apart from actual problem (Struct Name mismatch). 1. As Mentioned by Superman 2. Forward Declaration ! like this

struct s2; //forward Declaration
struct s1
{
CString str;
struct s2* ss2;
};

struct s2
{
int i;
CString name;
};

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow
Never mind - my own stupidity is the source of every "problem" - Mixture

cheers, Alok Gupta VC Forum Q&A :- I/IV Support CRY- Child Relief and You

Peter_in_2780

Richard MacCutchan wrote:

Try it.

#include <iostream.h>
struct a {
int aa;
struct b *pb;
};
struct b {
int bb;
struct a *pa;
};

#pragma argsused
int main(int argc, char* argv[])
{
struct a *xa = new struct a;
struct b *xb = new struct b;
xa->pb = xb;
xa->pb->bb = 5;
cout << xb->bb;
return 0;
}

compiles and runs in my world. OK, so I'm not (M$) politically correct - I'm currently using Borland Turbo C++. I vaguely remember K&R or Stroustrup talking about this kind of forward reference - a pointer is as big as a pointer, regardless of what it points to, so all the compiler has to do is accept the implicit declaration. btw, I don't want to get into a flame war about standards and compliance. :) [edit][rant]However, I do think the 1-votes are unwarranted. Note that the OP's problem was *never* with the struct definitions, but turned out to be a typo in later reference. Two of you jumped down my throat. Personally, I don't give a flying, but the youngsters watching this might get the wrong impression.[/rant][/edit]

Software rusts. Simon Stephenson, ca 1994.

modified on Tuesday, July 27, 2010 12:39 AM

Lost User · modified on Tuesday, July 27, 2010 12:39 AM

Well I did not jump down your throat, nor did I 1-vote you. I merely challenged your assertion that changing the order of the declarations would not make any difference. I do agree with you that we don't want to start a flame war with this.

It's time for a new signature.