DOC: Error C2213 Occurs When Base Is an Expression

ID: Q67882

The information in this article applies to:

Microsoft C/C++ Compiler (CL.EXE), included with:
- Microsoft C for MS-DOS, versions 6.0, 6.0a, 6.0ax
- Microsoft C/C++ for MS-DOS, version 7.0
- Microsoft Visual C++ for Windows, versions 1.0, 1.5
- Microsoft Visual C++ 32-bit Edition, versions 1.0, 2.0

SUMMARY

The following keywords were first introduced with Microsoft C version 6.0:

_based
_segment

Variables of type _segment are defined to hold a memory segment address.

With based variables, a base must be named to specify where the data resides. The base can be of type _segment, or can be a near or a far pointer. However, if the base is an expression, even of one of the types listed above, the following error is produced:

error C2213: illegal argument to _based

NOTE: In Microsoft Visual C++ 32-bit Edition, version 2.0, the _segment keyword was removed and the functionality of the __based keyword changed. In 32-bit compilations, pointers based on pointer addresses are the only forms of __based valid. In such compilations, these pointers are 32-bit displacements from a 32-bit base. For more information, search for "based addressing" in the online documentation included with Visual C++ 32-bit Edition.

MORE INFORMATION

Microsoft has confirmed that this is a restriction, although it is not documented as such.

The following examples illustrate the restriction:

This declaration is valid:


   _segment myseg;
   char _based( myseg ) *cptr;

The following declaration


   struct sample
   {
       _segment myseg;
   }rec;
   char _based( rec.myseg ) *cptr;

produces the following error:

error C2213: 'rec': illegal argument to _based
error C2059: syntax error: '.'

The following declaration


   _segment array[10];
   char _based( array[0] ) *cptr;

produces the following error:

error C2059: syntax error: '['

Additional query words: 6.00 6.00a 6.00ax 7.00 8.00 8.00c 9.00 1.00 1.50 2.00

Keywords : kbdocfix kbCompiler
Version : :1.0,1.5,2.0,6.0,6.0a,6.0ax
Platform : MS-DOS NT OS/2 WINDOWS
Issue type :