Struct array access

[Geky]

Can you tell me how I can access to an array of structure declared in
a file .cpp from any class?

 

[Victor Bazarov]

Can you tell me how I can access to an array of structure declared in
a file .cpp from any class?

By name, usually.

V

 

[Geky]

By name, usually.

V

I can't and I don't know why

example:

I declare an array of structure in a file. cpp.
I want to access to the structure from another file and then, in that
file, I declare the array of structure as "external".

when I try to use the structure my compiler returns me some errors
like:

error C2036: 'struct a_struct *': unknown size
error C2027: use of undefined type 'a_struct'
see declaration of 'a_struct'
error C2228: left of '. apple' must have class / struct / union type
Error executing cl.exe.

any idea?

 

[Geky]

By name, usually.

V

I can't and I don't know why

example:

I declare an array of structure in a file .cpp in a global class.
I want to access to the structure from another file in another class
and then, in that
file, I declare the array of structure as "external" like this

extern struct a_struct a_struct_ar[DIM_ARRAY];

when I try to use the structure my compiler returns me some errors
like:

error C2036: 'struct a_struct_ar *': unknown size
error C2027: use of undefined type 'a_struct_ar'
see declaration of 'a_struct_ar'
error C2228: left of '. apple' must have class / struct / union type
Error executing cl.exe.

any idea?

 

[Robert Hairgrove]

By name, usually.

V

You need to have an "extern" declaration in the other units. E.g.:

// foo.h
const int ARRAY_SIZE = 100;
struct MyStruct { /* whatever... */ };

// foo.cpp
#include "foo.h"
MyStruct MyStructArray[ARRAY_SIZE];

// bar.cpp
#include "foo.h"
extern MyStruct MyStructArray[ARRAY_SIZE];

 

[Victor Bazarov]

I can't and I don't know why

example:

I declare an array of structure in a file. cpp.
I want to access to the structure from another file and then, in that
file, I declare the array of structure as "external".

when I try to use the structure my compiler returns me some errors
like:

error C2036: 'struct a_struct *': unknown size
error C2027: use of undefined type 'a_struct'
see declaration of 'a_struct'
error C2228: left of '. apple' must have class / struct / union type
Error executing cl.exe.

any idea?

Oh, yes! See FAQ 5.8. You can find the FAQ Lite here:
http://www.parashift.com/c++-faq-lite/

It is *always* a good idea to check out the FAQ before posting.

V

 

[Geky]

It is *always* a good idea to check out the FAQ before posting.

heyyyy >.< Stay calm

 

[Geky]

<shrug> Stay ignorant

ahahahhaha ok ok funny guy ;-)

 

[Noah Roberts]

when I try to use the structure my compiler returns me some errors
like:

error C2036: 'struct a_struct *': unknown size
error C2027: use of undefined type 'a_struct'
see declaration of 'a_struct'
error C2228: left of '. apple' must have class / struct / union type
Error executing cl.exe.

Your compiler doesn't know what a_struct looks like.