KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q50703: C and Pascal Mixed Language: Declare C Libraries First

Article: Q50703
Product(s): See article
Version(s): 5.10   | 5.10
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | S_PASCAL S_LINK | mspl13_c
Last Modified: 30-NOV-1989

When doing mixed language programming with C Version 5.10 and Pascal
Version 4.00, be sure to use the /NOD and /NOE linker switches, and
then specifically link with the C libraries before the Pascal
libraries. This will prevent the linker from finding multiply defined
symbols.

The linker will often report error L2025 when linking with the Pascal
library first, depending on what functions are called from C. The
printf() function is one example of a run-time function that will
cause this problem. The problem occurs because some of the low-level
routines involved in both libraries have the same name.

The following example typifies the problems encountered:

For instance, say that the Pascal library contains an object module
with a routine called A, and the C library contains an object module
with routine A as well as routine B.

Furthermore, suppose the Pascal code makes a call to the A library
routine and the C code makes a call to the B library routine.

If the Pascal libraries are linked first, the A .OBJ will be found in
the Pascal library, then the A and B .OBJ will be brought in from the
C library to resolve the call to B. This results in the linker
receiving two copies of routine A, which causes the error. By linking
the C library first, only the one object module (with both A and B)
will be found, and the symbol will not be multiply defined.

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.