Thread: Function Error Question

Hello Everyone,
I was wondering if someone could give me some insight on what this error is trying to tell me?

passing argument 3 of 'FindLstn' from incompatible pointer type [enabled by default]

The function I'm using is:

Code:

FindLstn(GPIB0, Instruments, Result, 31);

Just to troubleshoot I tried dummy constants in each argument

Code:

FindLstn(1,2,3,4);

But it still returned an error.

I looked up in the header file and the function appears to be

Code:

void NI488CC FindLstn       (int boardID, const Addr4882_t * addrlist, Addr4882_t * results, size_t limit);

Which I believe has 4 arguments.

Thanks for any help!

I'm not gonna lie to you, I do not know what a pointer is but I will study it and get back to your questions.

Originally Posted by oogabooga

Do you know what a pointer is? What are the types of Instruments and Result?

Some documentation:
Linux GPIB Package Homepage
IEEE-488 - Wikipedia, the free encyclopedia

In particular:
FindLstn
MakeAddr

A pointer points to a memory location

Here are the types:

Code:

#define GPIB0 0
int Instruments[31];
int Result[31];
FindLstn(GPIB0, Instruments, Result, 31);

Are my argument syntax wrong?

Originally Posted by oogabooga

Yes. Your arguments are obviously wrong. Did you read the documentation I referenced? Look at this:

Code:

void FindLstn(int board_desc, const Addr4882_t padList[], Addr4882_t resultList[], int maxNumResults);

So Instruments and Result need to be Addr4882_t arrays, not int arrays. If you don't know what that is (or cannot figure it out yourself), then you probably don't know enough to be playing with this code. What exactly are you attempting to do?

No argument with respect of me not understanding the code (this is why I'm practicing) - no pun intended.

I am trying to compile the 4882query.c example which is distributed in the National Instruments 488.2 executable on NI-488.2 3.0.2 - National Instruments. I need to learn this code because I need to perform tedious repeated measurements on test equipment.

I appreciate your feedback.

I fixed it! I had changed the initial array around and screwed it up. I changed it back to:

Addr4882_t Instruments[32], // Array of primary addresses
Result[31]; // Array of listen addresses

and now it compiles.

Thanks for your help!