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<h1>#NoEnv <span class="ver">[v1.0.43.08+]</span></h1>

<p>Avoids checking empty variables to see if they are environment variables (recommended for all new scripts).</p>
<pre class="Syntax">#NoEnv</pre>
<p>Specifying the line <code>#NoEnv</code> anywhere in a script prevents empty variables from being looked up as potential environment variables. For example:</p>
<pre>#NoEnv
MsgBox %WinDir%</pre>
<p>The above would <strong>not</strong> retrieve the &quot;WinDir&quot; environment variable (though that could be solved by doing <code>WinDir := A_WinDir</code> near the top of the script).</p>
<p>Specifying <code>#NoEnv</code> is recommended for all new scripts because:</p>
<ol>
  <li>It significantly improves performance whenever empty variables are used in an expression or command. It also improves <a href="DllCall.htm">DllCall</a>'s performance when unquoted parameter types are used (e.g. int vs. &quot;int&quot;).</li>
  <li>It prevents script bugs caused by environment variables whose names unexpectedly match variables used by the script.</li>
  <li>AutoHotkey v2 will make this behavior the default.</li>
</ol>
<p>To help ease the transition to #NoEnv, the built-in variables <a href="../Variables.htm#ComSpec">Comspec</a> and <a href="../Variables.htm#ProgramFiles">ProgramFiles</a> have been added. They contain the same strings as the corresponding environment variables.</p>
<p>When #NoEnv is in effect, the script should use <a href="EnvGet.htm">EnvGet</a> to retrieve environment variables, or use built-in variables like <a href="../Variables.htm#WinDir">A_WinDir</a>.</p>
<h3>Related</h3>
<p><a href="EnvGet.htm">EnvGet</a>, <a href="../Variables.htm#ComSpec">Comspec</a>, <a href="../Variables.htm#ProgramFiles">ProgramFiles</a>, <a href="../Variables.htm#WinDir">A_WinDir</a></p>

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