MEX: no stdout in release

I build my mex file with VS2019. I do my output with

cout << "hi" << endl;

When I build in release version, it outputs fine to matlab's console; in debug build it doesn't.

[Lukas]

Same here. Is there any update on this?

[Zohar]

I use this:

https://github.com/zoharl3/output_viewer

Answer 1

[Harsh]

Hi @Lukas and @Zohar,

It seems you're attempting to print strings from C++ to MATLAB.

Here are a few alternatives you might consider:

• Use "mexPrintf " Instead of cout: You can replace "cout" with "mexPrintf " to print directly in MATLAB. Here's an example of how to use "mexPrintf":

#include "mex.h" 

void mexFunction(int nlhs, mxArray* plhs[], int nrhs, const mxArray* prhs[]) { 
    mexPrintf("This prints in MATLAB again!!\n"); 
} 

• Error Encountered in Visual Studio: On attempting the same, I noticed an issue where, after running the MEX function along with the C++ file, and then trying to rebuild, an error appears in Visual Studio.

Initially, I executed the MEX file in MATLAB. Subsequently, when I attempted to build again in Visual Studio, I encountered the following error:

This error occurs irrespective of whether you are in release or debug mode. Even when executing the MEX file from the release folder, the error persists.

• Solution: A simple way to resolve this issue is to restart MATLAB. After doing so, the build process is completed successfully.

(As shown here, the build completes successfully even in debug mode.)

I hope this information is helpful. Thank you!