Calling C++ functions from MATLAB

Dear MATLAB users,

I am successfully generating C++ executable from my MATLAB code, however when I try to call cout in order to display the value of a variable, I get "error C3861: 'cout': identifier not found" The line I am using is: coder.ceval('cout',iteration); where iteration is the variable.

I understand, that cout is a function provided with the iostream library. The only reason I can think of for this problem, is MATLAB not calling the iostream library. If this is the case, how to tell explicitly to MATLAB to include the library?

Thank you for time

Vladimir

[Kaustubha Govind]

How about if you change that to 'std::cout' instead? Also, you may want to create a header foo.hpp with the line:

#include <iostream>

And add foo.hpp to the "codegen" command.

Answer 1

[Ryan Livingston]

Please note that

 coder.ceval('std::cout',iteration)

will generate

 cout(10)

in the C++ code, assuming the value of iteration is 10. However, "std::cout" is not a function and "std::ostream" is not a functor so this line will fail to compile.

Here is an example of how this could be accomplished:

 function callCout()
 % Call << on cout.  Don't forget to null-terminate the string
 coder.ceval('std::operator<<',cout(),['Hello world!' char(0)]);

 % Call endl
 coder.ceval('endl', cout());

 function os = cout
 % Returns an opaque representing std::cout and inlines the value where needed
 coder.inline('always');
 os = coder.opaque('std::ostream', 'std::cout', 'HeaderFile', '<iostream>');

then compile with:

 c = coder.config('mex');
 c.CustomHeaderCode = '#include <iostream>';
 c.TargetLang = 'C++';
 codegen callCout -config c

and call the generated MEX

 callCout_mex()

Answer 2

[Vladimir]

Thank you both for the responses. In the end, I found it easier to call the printf command with coder.ceval. I inserted the header stdio.h to my code and that completed the task.

Thanks again.

vladimir

[Ryan Livingston]

Glad to hear that you found a solution.