Visual Fortran - Access Violation (ntdll.dll)

[visualfortranproject]

I have simple application that I have got to compile in FORTRAN. This grows into several files with multiple subroutines and functions and I need to call it from VB.

When I first compiled it (F5), I've got this error message:

Loaded 'ntdll.dll', no matching symbolic information found.
Loaded 'C:WINDOWSsystem32kernel32.dll', no matching symbolic information found.
The thread 0x874 has exited with code 0 (0x0).
The program 'C:ProgramasMicrosoft Visual StudioMyProjectsalvDebugalv.exe' has exited with code 0 (0x0).

So I placed a breakpoint and made it run step-by-step (F11). Then I've got this other error message:

Unhelded exception in alv.exe (NTDLL.DLL):0xC0000005: Access Violation.

How can I solve it?

[Jugoslav_Dujic]

Well, which line of code produced the Access violation?

Even if you see only assembly code, you can open "View/Debug windows/Call stack" window and browse for the offending line there. Then check the arguments.

See also this newsletter article.

Jugoslav

[visualfortranproject]

Hi there Joguslav!

First of all, thank you for your message.

I've tried to find out wich line of code was producing that error message and by using the call stack window I've found this:

NTDLL! 77f95559()
NTDLL! 77f45a6e()
KERNEL32! 77e5e323()
ALV! _heap_init + 23 bytes
ALV! mainCRTStartup + 94 bytes
KERNEL32! 77e614c7()

It is not very helpfull for me, unfortunately... anyway, the project name is alv and I could create the project and build the alv.exe to run it. But I still can't run it completely...

I will read the article you sent to me. Thanks a lot.

Thiago

[Jugoslav_Dujic]

It's not helpful to me either... but it's probably not the problem with a particular line of code, but rather some general compiler/library settings. Access violation occurs at the very startup, even before the first line of "visible" code (heap_init sounds like a function from C run-time library...).

I don't get the "call from VB" part -- is it a purely fortran .exe which is just executed from VB, a fortran dll within VB exe or... ?

As a wild guess, try changing Project/Settings/Fortran/Libraries/Use run time libraryand Project/Settings/C++/Code Generation/Use run-time library to something else (but same on both places) & rebuild. Does it make difference?

Jugoslav

[Steven_L_Intel1]

Go into the Fortran..Libraries settings and select any library kind except "debug multithread DLL". Just "multithread DLL" should work. Rebuild the project.

I have seen this happen when a .NET program calls a Visual Fortran DLL linked to the debug multithread DLL libraries.

[visualfortranproject]

Maybe I did not explain myself clearly. This is a project created in fortran. It is made of several routines that read a text file (input - *.txt) to calculate a concrete beam and then to present the results as another text file (output).

It was created by my professor and I am trying to run an example, but I get stuck with this errors.

I've seen on that article you sent me that this problem might be caused by a routine that tries to modify an constant. Visual Fortran of version 6 asks the linker to put constants in a read-only address space and windows NT/2000 honors this. Therefore, trying to modify a constant causes an error...

I've been looking for the statement that is causing this error but I can't find it. At the call stack window I can't understand what is written there and at the context in the debugger I get the same undecipherable words...

I'm a bit lost...

Thiago

[Jugoslav_Dujic]

But none of things mentioned inthe article do not apply in your case -- the crash occurs even before the first line of your code is executed, indicatinga problem with run-time library or like.

Did Steve's suggestion about changing RTL type work?

Jugoslav