<html lang="en"> <head> <title>Character Strings in Mex-Files - Untitled</title> <meta http-equiv="Content-Type" content="text/html"> <meta name="description" content="Untitled"> <meta name="generator" content="makeinfo 4.13"> <link title="Top" rel="start" href="index.html#Top"> <link rel="up" href="Mex_002dFiles.html#Mex_002dFiles" title="Mex-Files"> <link rel="prev" href="Working-with-Matrices-and-Arrays-in-Mex_002dFiles.html#Working-with-Matrices-and-Arrays-in-Mex_002dFiles" title="Working with Matrices and Arrays in Mex-Files"> <link rel="next" href="Cell-Arrays-with-Mex_002dFiles.html#Cell-Arrays-with-Mex_002dFiles" title="Cell Arrays with Mex-Files"> <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> <meta http-equiv="Content-Style-Type" content="text/css"> <style type="text/css"><!-- pre.display { font-family:inherit } pre.format { font-family:inherit } pre.smalldisplay { font-family:inherit; font-size:smaller } pre.smallformat { font-family:inherit; font-size:smaller } pre.smallexample { font-size:smaller } pre.smalllisp { font-size:smaller } span.sc { font-variant:small-caps } span.roman { font-family:serif; font-weight:normal; } span.sansserif { font-family:sans-serif; font-weight:normal; } --></style> </head> <body> <div class="node"> <a name="Character-Strings-in-Mex-Files"></a> <a name="Character-Strings-in-Mex_002dFiles"></a> <p> Next: <a rel="next" accesskey="n" href="Cell-Arrays-with-Mex_002dFiles.html#Cell-Arrays-with-Mex_002dFiles">Cell Arrays with Mex-Files</a>, Previous: <a rel="previous" accesskey="p" href="Working-with-Matrices-and-Arrays-in-Mex_002dFiles.html#Working-with-Matrices-and-Arrays-in-Mex_002dFiles">Working with Matrices and Arrays in Mex-Files</a>, Up: <a rel="up" accesskey="u" href="Mex_002dFiles.html#Mex_002dFiles">Mex-Files</a> <hr> </div> <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><span class="file">stringdemo.cc</span></samp>, is given in the file <samp><span class="file">mystring.c</span></samp>, as seen below. <pre class="example"><pre class="verbatim"> #include <string.h> #include "mex.h" void mexFunction (int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]) { mwIndex i, j; mwSize m, n; mxChar *pi, *po; if (nrhs != 1 || ! mxIsChar (prhs[0]) || mxGetNumberOfDimensions (prhs[0]) > 2) mexErrMsgTxt ("expecting 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> <p class="noindent">An example of its expected output is <pre class="example"> mystring(["First String"; "Second String"]) ⇒ s1 = Second String First String </pre> <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. </body></html>