Q107432: PRB: Inline Assembly C++ Function May Need Return Statement

Article: Q107432
Product(s): Microsoft C Compiler
Version(s): MS-DOS:7.0; :1.0,1.5,2.0
Operating System(s): 
Keyword(s): kbprb
Last Modified: 26-JUL-2001

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The information in this article applies to:

- Microsoft C/C++ for MS-DOS, version 7.0 
- Microsoft Visual C++, versions 1.0, 1.5 
- Microsoft Visual C++, version 2.0 
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SYMPTOMS
========


C++ functions containing inline assembly routines that store the return value in
the AX register may need a return statement added to the function. If the
function does not have a return statement, the following error is generated:

  C2561: 'function name' function must return a value

RESOLUTION
==========

To resolve this error, create a temporary variable and move the AX register to
this variable for the return statement. This will work around the C++
type-checking syntax. If you are using C++ version 8.0 that ships with Visual
C++ for Windows NT, then the EAX register must be used instead.

Sample Code
-----------

  /* Compile options needed: none
  */ 

  int func(void)
  {
    //int a;         //Remove this comment to eliminate the error.
    __asm
    {
      mov ax, 02h
      ;mov a, ax         //Remove this comment to eliminate the error.
    }
    //return a;         //Remove this comment to eliminate the error.
  }

  void main(void)
  {
    int a;
    a = func();
  }

Additional query words: 7.00 8.00 8.00c 9.00 1.00 1.50 2.00

======================================================================
Keywords          : kbprb 
Technology        : kbVCsearch kbAudDeveloper kbZNotKeyword8 kbvc150 kbvc100 kbZNotKeyword3 kbCVC700DOS kbVC200
Version           : MS-DOS:7.0; :1.0,1.5,2.0
Issue type        : kbprb

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