Q118396: PRB: putchar Fails in C Code Called from FORTRAN Application

Article: Q118396
Product(s): Microsoft Fortran Compiler
Version(s): 1.0,4.0
Operating System(s): 
Keyword(s): kbCompiler kbFL32 kbFortranPS
Last Modified: 03-NOV-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Fortran Powerstation 32 for Windows NT, versions 1.0, 4.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

In a mixed-language program, compiling the FORTRAN code using the /MD option
prevents the C Run Time function "putchar" from operating.

For Fortran PowerStation 4.0, the following warning message is generated:

  LINK: warning LNK4098: defaultlib "LIBC" conflicts with use of other libs;
  use /NODEFAULTLIB:library

CAUSE
=====

This behavior is by design. You cannot safely mix objects built for different
program execution models. In this case, putchar('c') is a macro that expands to
putc(c,stdout) and stdout is defined differently in MSVCRT.LIB than it is in the
statically linked libraries.

RESOLUTION
==========

To work around this problem, either

- Use the /MD option on the C code as well.

-or-  - Compile the Fortran code using /MT instead of using /MD.

MORE INFORMATION
================

To generate the problem, compile the C code using Visual C++ 32-bit Edition and
compile the FORTRAN program using option /MD. Include the C object module on the
compile line so that it is passed to the linker. The command lines used are as
follows:

     CL -c C_SAMPLE.C
     FL32 -MD F_SAMPLE.FOR C_SAMPLE.OBJ

Run the sample code. It fails to display the letter "c" after "in the dll".

The program will run without error if the FORTRAN program is compiled using the
/MT option instead of the /MD option.

Sample Code: FORTRAN
--------------------

  C Compile options needed: /MD

        INTERFACE TO SUBROUTINE csub [C,ALIAS:'_csub']()
        END
        WRITE(*,*) 'In the main'
        CALL csub()
        END

Sample Code: C
--------------


   
      #include <stdio.h>
     #include <string.h>

     #define DLLexport _declspec(dllexport)

     DLLexport void csub();
     void csub()
     {
        printf("\nIn the dll\n");
        putchar('c');
     }

Additional query words: visualc 1.00 4.00

======================================================================
Keywords          : kbCompiler kbFL32 kbFortranPS 
Technology        : kbAudDeveloper kbFortranSearch kbZNotKeyword2 kbFORTRANPower32100NT kbFORTRANPower32400NT
Version           : :1.0,4.0

=============================================================================

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