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Create host process for C++ MEX function



mh = mexhost creates a MEX host process that is used to run C++ MEX functions. The default process name is MATLABMexHost.

Use the feval method of the matlab.mex.MexHost object returned to execute C++ MEX functions in the MEX host process.


mh = mexhost("EnvironmentVariables",envVariables) sets environment variable with values defined in envVariables for the process.


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Create a host process and run a C++ MEX function in that process.

The arrayProduct.cpp C++ MEX file contains the source code for a function that multiplies an array by a scalar input and returns the resulting array. Open this file and save it on your MATLAB® path. Build the C++ MEX source file using the mex command. To set up the MEX build, follow the instructions in Build C++ MEX Programs.

mex arrayProduct.cpp

Create a host process. The mexhost function returns a matlab.mex.MexHost object.

mh = mexhost;

Use the feval method of the matlab.mex.MexHost object to evaluate the C++ MEX function in the host process.

result = feval(mh,"arrayProduct",10,[2,4,6,8])
result =

    20    40    60    80

You can use the MexHost object to find the identifier of the process created by the mexhost function.

mh = mexhost;
ans = 

Each call to mexhost creates a process.

Set the value of environment variable envName1 to envVal1 and the value of variable envName2 to envVal2.

s = ["envName1","envVal1"
mh = mexhost("EnvironmentVariables",s)
mh = 

  MexHost with properties:

             ProcessName: "MATLABMexHost"
       ProcessIdentifier: "19344"
               Functions: [0×0 string]
    EnvironmentVariables: "envName1"    "envVal1"
                          "envName2"    "envVal2"

Input Arguments

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Environment variables and values, specified as an n-by-2 string array. Non-ASCII characters are not supported. The first column is the name of the environment variable and the second column is the value.

Output Arguments

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Host process, returned as a matlab.mex.MexHost object. Use this process to run a C++ MEX function outside of the MATLAB process.

More About

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Process Life Cycle

MATLAB terminates the process when the object returned by mexhost is destroyed. MATLAB destroys the object when any of the following occur.

  • The MEX host variable returned by mexhost goes out of scope, causing MATLAB to destroy the object.

  • The delete method is called on the MEX host variable explicitly.

  • The clear function is called on the MEX host variable and there are no other references to the object.

  • The clear function is called with any of these options: clear java, clear classes, or clear all.

Unload C++ MEX Functions

To unload all C++ MEX functions from their host processes, call clear mex or clear functions. To unload a specific C++ MEX function all host processes running it, call clear on the function name. For more information, see the clear function and Out-of-Process Execution of C++ MEX Functions.

Version History

Introduced in R2019a