Matlab/Simulink: How to extract S-function parameter as std::string
This helper function allows you to extract a string parameter from an S-function in MATLAB/Simulink and return it as a std::string. It handles the case where the parameter might not be set or is not a string, returning a default value if necessary.
extract_sfunction_param.cpp
// Helper function to get string parameter from S-function parameters
static std::string extractSFunctionParameterAsString(SimStruct *S, int paramIndex, const std::string& defaultValue = "default") {
const mxArray* param = ssGetSFcnParam(S, paramIndex);
if (param == nullptr || !mxIsChar(param)) {
return defaultValue; // Default fallback
}
// Get string length and allocate buffer
mwSize nameLen = mxGetNumberOfElements(param) + 1;
char* nameBuffer = new char[nameLen];
// Extract string from MATLAB parameter
if (mxGetString(param, nameBuffer, nameLen) == 0) {
std::string result(nameBuffer);
delete[] nameBuffer;
return result;
} else {
delete[] nameBuffer;
return defaultValue;
}
}Don’t forget to set the number of parameters in your S-function using ssSetNumSFcnParams() in mdlInitializeSizes() and to define the parameter in your Simulink model:
example.cpp
static void mdlInitializeSizes(SimStruct *S) {
ssSetNumSFcnParams(S, 1); // Set number of parameters
// Example usage
std::string myParam = extractSFunctionParameterAsString(S, 0, "default_value");
// Use myParam as needed
}Check out similar posts by category:
Matlab/Simulink
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