Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Programming
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Databases
Mail Systems
openSolaris
Eclipse Documentation
Techotopia.com
Virtuatopia.com

How To Guides
Virtualization
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Windows
Problem Solutions

  




 

 

6.48. Unnamed struct/union fields within structs/unions.

For compatibility with other compilers, GCC allows you to define a structure or union that contains, as fields, structures and unions without names. For example:

struct {
  int a;
  union {
    int b;
    float c;
  };
  int d;
} foo;

In this example, the user would be able to access members of the unnamed union with code like foo.b. Note that only unnamed structs and unions are allowed, you may not have, for example, an unnamed int.

You must never create such structures that cause ambiguous field definitions. For example, this structure:

struct {
  int a;
  struct {
    int a;
  };
} foo;

It is ambiguous which a is being referred to with foo.a. Such constructs are not supported and must be avoided. In the future, such constructs may be detected and treated as compilation errors.

 
 
  Published under the terms of the GNU General Public License Design by Interspire