mxSetData (C)

Set pointer to data elements in nonnumeric mxArray

mxSetData is not recommended for numeric arrays. Use typed, data-access functions instead. For more information, see Version History.

C Syntax

#include "matrix.h"
void mxSetData(mxArray *pm, void *pa);

Description

Use mxSetData to set data elements for nonnumeric arrays only.

For numeric arrays, MathWorks recommends that you create MEX files and update existing MEX files to use the typed, data-access functions in the interleaved complex API. For more information, see:

• Typed Data Access in C MEX Files

• MATLAB Support for Interleaved Complex API in MEX Functions

• Upgrade MEX Files to Use Interleaved Complex API

• Example arrayFillSetData.c

To build the MEX file, call mex with the -R2018a option.

The mxSetData function does not free memory allocated for existing data. To free existing memory, call mxFree on the pointer returned by mxGetData.

Input Arguments

pm — Pointer to nonnumeric MATLAB^® array

mxArray *

Pointer to a nonnumeric MATLAB array, specified as mxArray *.

pa — Pointer to data array

void *

Pointer to the data array within an mxArray, specified as void *

The array must be in dynamic memory. Call mxCalloc to allocate this memory. Do not use the ANSI^® C calloc function, which can cause memory alignment issues leading to program termination.

Version History

Introduced before R2006a

R2018a: Results of mxSetData are different based on build option

For a complex numeric mxArray, the mxSetData function sets different values based on the mex build option.

If you build the MEX file with the default release-specific option (-R2017b), then the function sets the elements of the array to the real-only values.

If you build the MEX file with the -R2018a option, then:

• When pm is a real array, pa becomes the real component of pm.

• When pm is complex array, pa also must be complex. Otherwise, the elements of pa become interleaved real and imaginary values, not real-only values.