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<a name="Character-Strings-in-Mex_002dFiles"></a>
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<p>
Next: <a href="Cell-Arrays-with-Mex_002dFiles.html#Cell-Arrays-with-Mex_002dFiles" accesskey="n" rel="next">Cell Arrays with Mex-Files</a>, Previous: <a href="Working-with-Matrices-and-Arrays-in-Mex_002dFiles.html#Working-with-Matrices-and-Arrays-in-Mex_002dFiles" accesskey="p" rel="prev">Working with Matrices and Arrays in Mex-Files</a>, Up: <a href="Mex_002dFiles.html#Mex_002dFiles" accesskey="u" rel="up">Mex-Files</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Character-Strings-in-Mex_002dFiles-1"></a>
<h4 class="subsection">A.2.3 Character Strings in Mex-Files</h4>
<p>As mex-files do not make the distinction between single and double
quoted strings within Octave, there is perhaps less complexity in the
use of strings and character matrices in mex-files. An example of their
use that parallels the demo in <samp>stringdemo.cc</samp> is given in the
file <samp>mystring.c</samp>, as shown below.
</p>
<div class="example">
<pre class="verbatim">#include <string.h>
#include "mex.h"
void
mexFunction (int nlhs, mxArray *plhs[],
int nrhs, const mxArray *prhs[])
{
mwSize m, n;
mwIndex i, j;
mxChar *pi, *po;
if (nrhs != 1 || ! mxIsChar (prhs[0])
|| mxGetNumberOfDimensions (prhs[0]) > 2)
mexErrMsgTxt ("ARG1 must be a char matrix");
m = mxGetM (prhs[0]);
n = mxGetN (prhs[0]);
pi = mxGetChars (prhs[0]);
plhs[0] = mxCreateNumericMatrix (m, n, mxCHAR_CLASS, mxREAL);
po = mxGetChars (plhs[0]);
for (j = 0; j < n; j++)
for (i = 0; i < m; i++)
po[j*m + m - 1 - i] = pi[j*m + i];
}
</pre><pre class="example">
</pre></div>
<p>An example of its expected output is
</p>
<div class="example">
<pre class="example">mystring (["First String"; "Second String"])
⇒ Second String
First String
</pre></div>
<p>Other functions in the mex interface for handling character strings are
<code>mxCreateString</code>, <code>mxArrayToString</code>, and
<code>mxCreateCharMatrixFromStrings</code>. In a mex-file, a character string
is considered to be a vector rather than a matrix. This is perhaps an
arbitrary distinction as the data in the mxArray for the matrix is
consecutive in any case.
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