---
title: "Anonymous Class Types | Microsoft Docs"
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---
# Anonymous Class Types
Classes can be anonymous — that is, they can be declared without an *identifier*. This is useful when you replace a class name with a `typedef` name, as in the following:  
  
```  
typedef struct  
{  
    unsigned x;  
    unsigned y;  
} POINT;  
```  
  
> [!NOTE]
>  The use of anonymous classes shown in the previous example is useful for preserving compatibility with existing C code. In some C code, the use of `typedef` in conjunction with anonymous structures is prevalent.  
  
 Anonymous classes are also useful when you want a reference to a class member to appear as though it were not contained in a separate class, as in the following:  
  
```  
struct PTValue  
{  
    POINT ptLoc;  
    union  
    {  
        int  iValue;  
        long lValue;  
    };  
};  
  
PTValue ptv;  
```  
  
 In the preceding code, `iValue` can be accessed using the object member-selection operator (**.**) as follows:  
  
```  
int i = ptv.iValue;  
```  
  
 Anonymous classes are subject to certain restrictions. (For more information about anonymous unions, see [Unions](../cpp/unions.md).) Anonymous classes:  
  
-   Cannot have a constructor or destructor.  
  
-   Cannot be passed as arguments to functions (unless type checking is defeated using ellipses).  
  
-   Cannot be returned as return values from functions.  
  
## Anonymous structs  
  
### Microsoft Specific  
 A Microsoft C extension allows you to declare a structure variable within another structure without giving it a name. These nested structures are called anonymous structures. C++ does not allow anonymous structures.  
  
 You can access the members of an anonymous structure as if they were members in the containing structure.  
  
```  
// anonymous_structures.c  
#include <stdio.h>  
  
struct phone  
{  
    int  areacode;  
    long number;  
};  
  
struct person  
{  
    char   name[30];  
    char   gender;  
    int    age;  
    int    weight;  
    struct phone;    // Anonymous structure; no name needed  
} Jim;  
  
int main()  
{  
    Jim.number = 1234567;  
    printf_s("%d\n", Jim.number);     
}  
//Output: 1234567  
```  
  
**END Microsoft Specific**