User`s manual

Examples of C MEX-Files

2-11

/* Call the timestwo_alt subroutine. */

timestwo_alt(y,x);

}

This example passes the input scalar x by value into the timestwo_alt

subroutine, but passes the output scalar

y by reference.

Passing Strings

Any MATLAB data type can be passed to and from MEX-files. For example,

this C code accepts a string and returns the characters in reverse order.

/* $Revision: 1.10 $ */

/*=============================================================

* revord.c

* Example for illustrating how to copy the string data from

* MATLAB to a C-style string and back again.

* Takes a string and returns a string in reverse order.

* This is a MEX-file for MATLAB.

*============================================================*/

#include "mex.h"

void revord(char *input_buf, int buflen, char *output_buf)

{

int i;

/* Reverse the order of the input string. */

for(i = 0; i < buflen-1; i++)

*(output_buf+i) = *(input_buf+buflen-i-2);

}

In this example, the API function mxCalloc replaces calloc, the standard C

function for dynamic memory allocation.

mxCalloc allocates dynamic memory

using MATLAB’s memory manager and initializes it to zero. You must use

mxCalloc in any situation where C would require the use of calloc. The same

is true for

mxMalloc and mxRealloc; use mxMalloc in any situation where C

would require the use of

malloc and use mxRealloc where C would require

realloc.