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<h1id="trycatch">Try/Catch</h1>
<blockquote>
<p>TRY/CATCH is used to trap errors allowing a program to recover
without having to be restarted.</p>
</blockquote>
<p><strong>TRY</strong></p>
<p>The TRY statement introduces a TRY/CATCH block.</p>
<p><strong>CATCH [var | expr]</strong></p>
<p>The CATCH statement is used to CATCH an run-time error. This is
typically used with errors raised when calling a file system command
that cannot be completed, for example attempting to open a non-existent
file.</p>
<p>The CATCH statement has two modes. You can supply a variable argument
to store the error string. Alternatively you can supply an expression.
When the raised error matches the (String) expression, the error will be
caught.</p>
<p>When using the expression mode, you can supply a succession of CATCH
statements to handle various error messages separately.</p>
<p><strong>END TRY</strong></p>
<p>The <strong>END TRY</strong> statement marks the end of a TRY/CATCH
block.</p>
<p><strong>THROW</strong></p>
<p>The THROW command (previously known as <strong>RTE</strong>) is used
to initiate a catch-able error. If there is no surrounding TRY/CATCH
block, THROW can be used to abort the program.</p>
<p><strong>Example</strong></p>
<divclass="sourceCode" id="cb1"><pre
class="sourceCode smallbasic"><codeclass="sourceCode smallbasic"><spanid="cb1-1"><ahref="#cb1-1" aria-hidden="true" tabindex="-1"></a><spanclass="kw">try</span></span>
<spanid="cb1-2"><ahref="#cb1-2" aria-hidden="true" tabindex="-1"></a><spanclass="fu">open</span><spanclass="st">"com2000:"</span><spanclass="kw">AS</span> #<spanclass="dv">1</span></span>
<spanid="cb1-3"><ahref="#cb1-3" aria-hidden="true" tabindex="-1"></a><spanclass="kw">catch</span> err</span>
<spanid="cb1-4"><ahref="#cb1-4" aria-hidden="true" tabindex="-1"></a> ? <spanclass="st">"in catch: open failed"</span>;err</span>
<spanid="cb1-5"><ahref="#cb1-5" aria-hidden="true" tabindex="-1"></a><spanclass="kw">end try</span></span></code></pre></div>
<p><strong>Try/Catch in other languages</strong></p>
<ul>
<li><a
href="http://www.cplusplus.com/doc/tutorial/exceptions">C++</a></li>
<li><a
href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/try...catch">Javascript</a></li>
<li><a
href="http://msdn.microsoft.com/en-AU/library/fk6t46tz.aspx">Visual
Basic</a></li>
</ul>
<p><strong>History</strong></p>
<p>The TRY/CATCH mechanism was introduced in version 0.11.15.</p>
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This page was last edited on Sat, 9 Sep 2023 22:31:16 +0200
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