<html lang="en"> <head> <title>The @code{try} Statement - 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="Statements.html#Statements" title="Statements"> <link rel="prev" href="The-_0040code_007bunwind_005fprotect_007d-Statement.html#The-_0040code_007bunwind_005fprotect_007d-Statement" title="The @code{unwind_protect} Statement"> <link rel="next" href="Continuation-Lines.html#Continuation-Lines" title="Continuation Lines"> <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="The-%3ccode%3etry%3c%2fcode%3e-Statement"></a> <a name="The-_003ccode_003etry_003c_002fcode_003e-Statement"></a> <p> Next: <a rel="next" accesskey="n" href="Continuation-Lines.html#Continuation-Lines">Continuation Lines</a>, Previous: <a rel="previous" accesskey="p" href="The-_003ccode_003eunwind_005fprotect_003c_002fcode_003e-Statement.html#The-_003ccode_003eunwind_005fprotect_003c_002fcode_003e-Statement">The <code>unwind_protect</code> Statement</a>, Up: <a rel="up" accesskey="u" href="Statements.html#Statements">Statements</a> <hr> </div> <h3 class="section">10.9 The <code>try</code> Statement</h3> <p><a name="index-g_t_0040code_007btry_007d-statement-578"></a><a name="index-g_t_0040code_007bcatch_007d-579"></a><a name="index-g_t_0040code_007bend_005ftry_005fcatch_007d-580"></a> In addition to unwind_protect, Octave supports another limited form of exception handling. <p>The general form of a <code>try</code> block looks like this: <pre class="example"> try <var>body</var> catch <var>cleanup</var> end_try_catch </pre> <p class="noindent">where <var>body</var> and <var>cleanup</var> are both optional and may contain any Octave expressions or commands. The statements in <var>cleanup</var> are only executed if an error occurs in <var>body</var>. <p>No warnings or error messages are printed while <var>body</var> is executing. If an error does occur during the execution of <var>body</var>, <var>cleanup</var> can use the function <code>lasterr</code> to access the text of the message that would have been printed. This is the same as <code>eval (</code><var>try</var><code>, </code><var>catch</var><code>)</code> but it is more efficient since the commands do not need to be parsed each time the <var>try</var> and <var>catch</var> statements are evaluated. See <a href="Errors-and-Warnings.html#Errors-and-Warnings">Errors and Warnings</a>, for more information about the <code>lasterr</code> function. <p><a name="index-continuation-lines-581"></a><a name="index-g_t_0040code_007b_002e_002e_002e_007d-continuation-marker-582"></a><a name="index-g_t_0040code_007b_005c_007d-continuation-marker-583"></a> </body></html>