• novice2 <sorry noem.ail> Dec 29 2006
• Thomas Kuehne <thomas-dloop kuehne.cn> Dec 29 2006
• Derek Parnell <derek psych.ward> Dec 29 2006

novice2 <sorry noem.ail> writes:

Hello. Could please anybody explain me syntax to access to nested
structure/union members? In Windows API translated headers thearis
situation - anonimous union nested in structure. This is minimal
trivial extracted example:

//dmd\html\d\struct.html: "anonymous structs/unions are allowed as
members of other structs/unions"

struct Stru
{
  int a;
  union Uni
  {
    int b;
    int c;
  };
}


void main()
{
  Stru s;

  //s.Uni.b = 2; // Error: need 'this' to access member b

  //s.b = 2;     // Error: no property 'b' for type 'Stru'
                 // Error: constant (s).b is not an lvalue
}


How i can access to s.Uni.b ?
Thanks for any advises.

Thomas Kuehne <thomas-dloop kuehne.cn> writes:

novice2 <sorry noem.ail> schrieb:
 Hello. Could please anybody explain me syntax to access to nested
 structure/union members? In Windows API translated headers thearis
 situation - anonimous union nested in structure. This is minimal
 trivial extracted example:

 //dmd\html\d\struct.html: "anonymous structs/unions are allowed as
 members of other structs/unions"

 struct Stru
 {
   int a;
   union Uni 
   {
     int b;
     int c;
   };
 }


This union is named "Stru.Uni", it isn't anonymous.

The anonymous version is:
 struct Stru
 {
   int a;
   union
   {
     int b;
     int c;
   };
 }


Thomas

Derek Parnell <derek psych.ward> writes:

On Fri, 29 Dec 2006 14:52:59 +0000 (UTC), novice2 wrote:

 Hello. Could please anybody explain me syntax to access to nested
 structure/union members? In Windows API translated headers thearis
 situation - anonimous union nested in structure. This is minimal
 trivial extracted example:
 
 //dmd\html\d\struct.html: "anonymous structs/unions are allowed as
 members of other structs/unions"
 
 struct Stru
 {
   int a;
   union Uni
   {
     int b;
     int c;
   };
 }
 
 
 void main()
 {
   Stru s;
 
   //s.Uni.b = 2; // Error: need 'this' to access member b
 
   //s.b = 2;     // Error: no property 'b' for type 'Stru'
                  // Error: constant (s).b is not an lvalue
 }
 
 
 How i can access to s.Uni.b ?
 Thanks for any advises.


Either use anonymous struct or declare and instance of the struct.

Eg. (Anonymous)

 struct Stru
 {
   int a;
   union  // Don't give this a name.
   {
     int b;
     int c;
   };
 }
 
 
 void main()
 {
   Stru s;
   s.b = 2;
 }


Eg. (Named)

 struct Stru
 {
   int a;
   union  Uni // Named, therefore must instantiate it.
   {
     int b;
     int c;
   };
   Uni u;
 }
 
 
 void main()
 {
   Stru s;
   s.u.b = 2;
 }

-- 
Derek Parnell