libstruct (External Interfaces Reference)

Construct structure as defined in external library

Syntax

s = libstruct('structtype')
s = libstruct('structtype', mlstruct)

Description

s = libstruct('type') returns a libstruct object s that is a MATLAB object designed to resemble a C structure of type structtype. The structure type, structtype, is defined in an external library that must be loaded into MATLAB using the loadlibrary function. All fields of s are set to zero.

s = libstruct('structtype', mlstruct) returns a libstruct object s with its fields initialized from MATLAB structure, mlstruct.

The libstruct function essentially creates a C-like structure that you can pass to functions in an external library. You can handle this structure in MATLAB as you would a true MATLAB structure.

Examples

This example performs a simple addition of the fields of a structure. The function addStructFields is defined in the MATLAB sample shared library, shrlibsample.

Here is the C function:

double addStructFields(struct c_struct st)
{
    double t = st.p1 + st.p2 + st.p3;
    return t;
}

Start by loading the shrlibsample library and creating MATLAB structure, sm:

addpath([matlabroot '\extern\examples\shrlib'])
loadlibrary shrlibsample.dll shrlibsample.h

sm.p1 = 476;   sm.p2 = -299;   sm.p3 = 1000;

Construct a libstruct object sc that uses the c_struct template:

sc = libstruct('c_struct', sm);

get(sc)
    p1: 476
    p2: -299
    p3: 1000

Now call the function, passing the libstruct object, sc:

calllib('shrlibsample', 'addStructFields', sc)
ans =
    1177

unloadlibrary shrlibsample

Note In most cases, you can pass a MATLAB structure and MATLAB will automatically convert the argument to a C structure. See Structures, in the MATLAB documentation for more information.

libpointer loadlibrary