<html lang="en"> <head> <title>Accessing Global Variables in Oct-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="Oct_002dFiles.html#Oct_002dFiles" title="Oct-Files"> <link rel="prev" href="Sparse-Matrices-in-Oct_002dFiles.html#Sparse-Matrices-in-Oct_002dFiles" title="Sparse Matrices in Oct-Files"> <link rel="next" href="Calling-Octave-Functions-from-Oct_002dFiles.html#Calling-Octave-Functions-from-Oct_002dFiles" title="Calling Octave Functions from Oct-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="Accessing-Global-Variables-in-Oct-Files"></a> <a name="Accessing-Global-Variables-in-Oct_002dFiles"></a> <p> Next: <a rel="next" accesskey="n" href="Calling-Octave-Functions-from-Oct_002dFiles.html#Calling-Octave-Functions-from-Oct_002dFiles">Calling Octave Functions from Oct-Files</a>, Previous: <a rel="previous" accesskey="p" href="Sparse-Matrices-in-Oct_002dFiles.html#Sparse-Matrices-in-Oct_002dFiles">Sparse Matrices in Oct-Files</a>, Up: <a rel="up" accesskey="u" href="Oct_002dFiles.html#Oct_002dFiles">Oct-Files</a> <hr> </div> <h4 class="subsection">A.1.7 Accessing Global Variables in Oct-Files</h4> <p>Global variables allow variables in the global scope to be accessed. Global variables can easily be accessed with oct-files using the support functions <code>get_global_value</code> and <code>set_global_value</code>. <code>get_global_value</code> takes two arguments, the first is a string representing the variable name to obtain. The second argument is a boolean argument specifying what to do in the case that no global variable of the desired name is found. An example of the use of these two functions is <pre class="example"><pre class="verbatim"> #include <octave/oct.h> DEFUN_DLD (globaldemo, args, , "Global demo.") { int nargin = args.length (); octave_value retval; if (nargin != 1) print_usage (); else { std::string s = args(0).string_value (); if (! error_state) { octave_value tmp = get_global_value (s, true); if (tmp.is_defined ()) retval = tmp; else retval = "Global variable not found"; set_global_value ("a", 42.0); } } return retval; } </pre></pre> <p>An example of its use is <pre class="example"> global a b b = 10; globaldemo ("b") ⇒ 10 globaldemo ("c") ⇒ "Global variable not found" num2str (a) ⇒ 42 </pre> </body></html>