Create C++ Header File from Strongly Typed MATLAB Function

This example shows how to create a C++ header file from a strongly typed MATLAB^® function and integrate it with sample C++ application code.

Create Function in MATLAB

Create a MATLAB function named stronglyTypedFactorial.m with this code:

function fact = stronglyTypedFactorial(n)
arguments
    n (1,1) uint64 {mustBeReal, mustBeLessThan(n,22)}
end
fact = 1;
for i = 1:n
    fact = fact*i;
end
end

Test the function at the MATLAB command prompt.

stronglyTypedFactorial(5)

ans =
  uint64
   120

Generate C++ Header File

Generate the C++ header file:

matlab.engine.typedinterface.generateCPP("myFactorial.hpp",Functions="stronglyTypedFactorial")

0 class(es) and 1 function(s) written to myFactorial.hpp

The function creates the myFactorial.hpp header file that defines a C++ data array accepting an argument n of type uint64_t.

matlab::data::Array stronglyTypedFactorial(std::shared_ptr<MATLABControllerType> _matlabPtr, uint64_t n)

This uint64_t mapping matches the strongly typed uint64 data type of the MATLAB argument n.

n (1,1) uint64 {mustBeReal, mustBeLessThan(n,22)}

The interface verifies that the input meets the mustBeReal argument. At runtime, the MATLAB stronglyTypedFactorial function verifies that the input meets the mustBeLessThan(n,22) argument. For more information, see Data Type Mappings Between C++ and Strongly Typed MATLAB Code.

 myFactorial.hpp

#include "MatlabTypesInterface.hpp"

matlab::data::Array stronglyTypedFactorial(std::shared_ptr<MATLABControllerType> _matlabPtr, uint64_t n) { 
    matlab::data::ArrayFactory _arrayFactory;
    matlab::data::ArrayDimensions _dims1 = {1, 1};
    std::vector<matlab::data::Array> _args = {
        _arrayFactory.createArray<uint64_t>(_dims1, {n}) };
    matlab::data::Array _result = _matlabPtr->feval(u"stronglyTypedFactorial", _args);
    return _result;
}

Integrate C++ MATLAB Data API Header with C++ Application

Create a C++ application code file named factApp.cpp with this code. When writing your C++ application, you must include:

• MatlabEngine.hpp before any generated header files.

• The myFactorial.hpp file generated by the matlab.engine.typedinterface.generateCPP function.

 factApp.cpp

// Include header files
#include "MatlabEngine.hpp"
#include "myFactorial.hpp"     // Generated typed interface to MATLAB code
#include <iostream>

int main()
{
    // Connect to MATLAB
    std::shared_ptr<matlab::engine::MATLABEngine> matlabPtr = matlab::engine::startMATLAB();

    // Call the stronglyTypedFactorial MATLAB function to compute 5!
    // 5 is arbitrarily chosen for demonstration purposes.
    matlab::data::TypedArray<uint64_t> output = stronglyTypedFactorial(matlabPtr, 5);
    std::cout << "Factorial of 5 is " << output[0] << "\n";
    return 0;
}

Verify that you have selected a supported C++ compiler.

mex -setup -client engine C++

Compile and link the C++ application at the MATLAB command prompt. For more information, see Build C++ Engine Programs.

mex -client engine factApp.cpp

Determine the run-time library path. For an example built on Windows^®, type:

rtpath = fullfile(matlabroot,'extern','bin','win64')

Set the run-time library path from the system prompt, substituting the value for rtpath. For example:

set PATH=C:\Program Files\MATLAB\R2022a\extern\bin\win64;%PATH%

Run the application.

factApp.exe

Factorial of 5 is 120