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copied!<p>Logically your failing code equates to</p> <pre><code>setlocal enableDelayedExpansion ( set VAR1=success set VAR2=VAR1 set VAR3=!%VAR2%! echo VAR3=!VAR3! ) </code></pre> <p>As has already been pointed out in previous answers and comments, you can't assign a value to VAR2 and then access the value using %VAR2% within the same code block because %VAR2% is expanded during the parsing phase of the code block, at which point the value is not what you want (probably undefined).</p> <p>But you need a second level of expansion in addition to !VAR2! to get the result you want. I know of three solutions.</p> <p><strong>1)</strong> This solution works, but it is not recommended because it is slow.</p> <pre><code>setlocal enableDelayedExpansion ( set VAR1=success set VAR2=VAR1 call set VAR3=%%!VAR2!%% echo VAR3=!VAR3! ) </code></pre> <p>Prior to the execution of the CALL, each %% is reduced to %, and !VAR2! becomes VAR1. Thus the called statement becomes <code>set VAR3=%VAR1%</code>, and the called statement is reparsed through the %var% expansion phase, so you get your desired result.</p> <p>BUT - CALL is relatively very expensive. When used in a loop it can cause severe performance degradation. jeb provides a good demonstration and explanation at <a href="http://www.dostips.com/forum/viewtopic.php?f=3&t=1947&p=8386#p8386" rel="nofollow" title="CALL me, or better avoid call">CALL me, or better avoid call</a></p> <p><strong>1a)</strong> There is a variation of the CALL solution where you call a :LABELed subroutine. Because the subroutine is parsed after the call, you can simply use <code>set VAR3=!%VAR2%!</code>. But again, this uses CALL so it is relatively slow and not recommended.</p> <p><strong>2)</strong> This general solution works, and is <em>MUCH</em> faster in comparison. It uses a FOR variable for the second level of expansion. This is the recommended solution.</p> <pre><code>setlocal enableDelayedExpansion ( set VAR1=success set VAR2=VAR1 for /f %%A in ("!VAR2!") do set VAR3=!%%A! echo VAR3=!VAR3! ) </code></pre> <p><strong>3)</strong> If the value of VAR1 is known to be an integer, then there is a special case solution using <code>SET /A</code></p> <pre><code>setlocal enableDelayedExpansion ( set VAR1=999 set VAR2=VAR1 set /a VAR3=!VAR2! echo VAR3=!VAR3! ) </code></pre> <p>The SET /A command has its own built in expansion of variables that takes place after delayed expansion, and no punctuation is needed.</p>

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