LabWindows/CVI

[lakeshoretest2…]

Hello community,

I am new to Labwindows (using version 6.0.0).

I am trying to run an inherited project which is configured to debug setting, but the project will not successfully build.

The project has 5 files: 2 .h files, 1 .uir file, 1 .c, and 1 .fp.

When I try to run the .exe, the BUILD ERRORS window opens with the message:

Project link error.
Undefined symbol '_main' referenced in "c:\program files\national instruments\measurementstudio\cvi\bin\cvistart.lib"

I've checked the help files, online forums, and google, but can't find an answer to the solution.

Where and how do I start the debug process for this error?

Is there an editor where I can view the contents of cvistart.lib?

Is this particular error due to the "_" preceding main? I'm thinking more than likely it is something with my code. I have successfully run some of the included CVI sample projects, but others have given me errors.

Any help out there?

Thanks.

LT2005

[bilalD]

If you are creating an exe, you need have a function main() or WinMain() defined in your application. The prototype is as follows

int main (int argc, char *argv[])
int __stdcall WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpszCmdLine, int nCmdShow)

This is where the exe execution starts. Check to see if you have a main defined.

If this project was initially meant to be a dll with exported functions, change the project target settings to specify that. To do this, go to Build >> Target Type, and specify Dynamic Link Library.

Hope this helps

[Wendy L]

Hello LT2005,

The _main link error usually occurs when a main function is not declared in one of your included source files. The cvistart.lib function is throwing an error because CVI will look for a main() function as a start point for you application.

The main function might look something like:
int main(int argc, char*argv[])
{
//Your code here

}


First make sure that there is a main function in your .c file and see if that resolves the error.

Also, which shipping examples did you try running and what errors were returned?

Thanks.

[lakeshoretest2…]

Bilal and Wendy:

Thank you for responding.

It appears that I have two calls to main in the .c file found in my project. However, the call to main follows several functions. Is that a problem?

Here is the code:

#if(0) /* to create a stand-alone version of the Pwr interactive control */
void main(void)
{
/*** A Few lines of code found here; I removed to shorten this post.
}
#endif


#if(0) /* perform sw driver selftest fault insertion and verification */
void main(void)
{
/*** A Few lines of code found here; I removed to shorten this post.
}
#endif

Bilal:
Should I still attempt building this project as a .dll?

Wendy:
I will need to revisit the examples I tested and report back to you.

Thanks,

LT2005

[Al S]

The compiler never sees a main().
#if is a preprocessor directive (a command to the compiler). It is used to conditionally select code to pass to the compiler. Code within an #if structure that is not selected does not get compiled.
#if(0) is never true, so main() is never compiled.
You need to select one of the mains and remove #if and #endif statements or change #if(0) to #if(1).
The two mains you see are alternate definitions. They are not calls to main. You program never calls main: the code starts in main automatically.
main does not need to be the first function defined in your .c file. Where it is defined is more a question of style. Many programmers place main toward the end of the source file.

[lakeshoretest2…]

Al,

You are exactly right, thank you for the response. And I realized the problem right after posting - seems so trivial now. I did as you say, replaced the zero with a 1 and the program compiled. Now I have other problems with function calls, but that is neither here nor there.

Thanks.