Understanding DAQmxErrChk(functionCall)

[SKSV]

I  have seen this line in a couple of examples #define DAQmxErrChk(functionCall) if( DAQmxFailed(error=(functionCall)) ) goto Error; else

I would like to understand the purpose of this statement in the code. The argument functionCall to the function DAQmxErrChk isn't declared anywhere. I have searched for documentation that explains the purpose of the DAQmxErrChk but couldn't find any.

Any help is appreciated.

[RobertoBozzolo · Accepted solution]

This isn't a function call, it's a macro! When you run your project the preprocessor comes in first and replaces every occurrence of the macros with their proper code; functionCall is the placeholder for the function enclosed in macro brackets. Thus, the code

#define DAQmxErrChk(functionCall) if( DAQmxFailed(error=(functionCall)) ) goto Error; else

DAQmxErrChk (DAQmxStartTask(taskHandle));

gets actually translated to

if( ((error=(DAQmxStartTask(taskHandle)))<0) ) goto Error; else;

(note that DAQmxFailed is actually another macro that is defined in nidaqmx.h)

You can see how code is handled by the proprocessor by running Options >> Preprocess Source File menu function and looking at the new code window that is generated.

[SKSV]

For some reason I cannot see Accept as solution Button

[SKSV]

Never mind I found it after replying to the post above