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<title>"try" Statement - TMBASIC</title>
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<div class="backlinks"><a href="doc.html">TMBASIC Documentation</a></div><h1><span class="tt">try</span> Statement</h1><span class="tt">try</span> ... <span class="tt">catch</span> ... <span class="tt">end try</span> blocks are how errors are handled in TMBASIC.
Errors are raised using the <a href="statement_throw.html"><span class="tt">throw</span></a> statement.
If an error is raised inside a <span class="tt">try</span> block, then program execution will jump to the <span class="tt">catch</span> block in order to handle the error.
You can display the error to the user or take some other corrective action like retrying.
Use <a href="statement_rethrow.html"><span class="tt">rethrow</span></a> in your <span class="tt">catch</span> block to re-raise an error that you want to pass up to the calling code.<h2>Syntax</h2><div class="code"><div>try</div><div><span class="indent"> </span><TRY-STATEMENTS></div><div>catch</div><div><span class="indent"> </span><CATCH-STATEMENTS></div><div>end try</div></div><ul><li><span class="tt"><TRY-STATEMENTS></span> is the code to execute that may potentially fail with an error.</li><li><span class="tt"><CATCH-STATEMENTS></span> is the code to execute if an error is raised inside the <span class="tt">try</span> block. It will not be executed if the <span class="tt">try</span> block executes successfully.</li></ul><h2>Usage</h2>The following example is contrived to show both the "thrower" and "catcher" sides of a raised error.
The message string provided to the <span class="tt">throw</span> statement can be retrieved from the <a href="procedure_errormessage.html">ErrorMessage</a> function inside your <span class="tt">catch</span> block.
The <a href="procedure_errorcode.html">ErrorCode</a> function can be used to retrieve the error code, which is optional for your own <span class="tt">throw</span> statements but is always available for TMBASIC-generated errors.<div class="paragraphBreak"></div><div class="code"><div>try</div><div><span class="indent"> </span>throw 1234, <span class="string">"This is an error!"</span></div><div>catch</div><div><span class="indent"> </span>print ErrorCode(); <span class="string">": "</span>; ErrorMessage()</div><div>end try</div></div>In real code, the <span class="tt">throw</span> statement will be inside a function or subroutine, and the <span class="tt">catch</span> block will be in the calling code.
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