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Enclose it in a try/catch block and catch the exception.
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Is that standard practice? &nbsp;I thought it would slow down the app or use up memory unnecessarily.
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I want to write to a file using a streamwriter.<br />
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<pre><code class="code-1 nolinks" id="code-10-29099518-1"><span>using (StreamWriter sw = new StreamWriter(@&quot;D:\Documents\MathsPrograms\Prime2.csv&quot;, false))</span>
<span>                {</span>
<span>}</span>
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How can I get the program to give an error message if the file is locked eg another program is writing to it, or a user has the file open in Excel?
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I want to write to a file using a streamwriter.

(CODE)

How can I get the program to give an error message if the file is locked eg another program is writing to it, or a user has the file open in Excel?

Checking if file is open before writing to it.

C# is an object-oriented programming language created in conjunction with Microsoft’s .NET framework. Compilation is usually done into the Microsoft Intermediate Language (MSIL), which is then JIT-compiled to native code (and cached) during execution in the Common Language Runtime (CLR).