Powershell rename-item, replace old name using functions
<p>I have a list of files:</p>

<pre><code>PS S:\temp&gt; dir


    Directory: S:\temp


Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---         3/28/2016   2:07 AM          0 00001_asdfasdfsa df.txt
-a---         3/28/2016   2:07 AM          0 00002_asdfasdfsa df - Copy (3).txt
-a---         3/28/2016   2:07 AM          0 00003_asdfasdfsa df - Copy.txt
-a---         3/28/2016   2:07 AM          0 00004_asdfasdfsa df - Copy (6).txt
-a---         3/28/2016   2:07 AM          0 00005_asdfasdfsa df - Copy (5).txt
-a---         3/28/2016   2:07 AM          0 00006_asdfasdfsa df - Copy (4).txt
-a---         3/28/2016   2:07 AM          0 00007_asdfasdfsa df - Copy (2).txt
-a---         3/28/2016   2:07 AM          0 700006_asdfasdfsa df - Copy (4) - Copy.txt


PS S:\temp&gt;
</code></pre>

<p>I want to renamem those that start with five numbers and an underline. The new name will add a number I specified to the leading numbers of those file names. For example, if I add 10, the new names would be:</p>

<pre><code>PS S:\temp&gt; dir


    Directory: S:\temp


Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---         3/28/2016   2:07 AM          0 00011_asdfasdfsa df.txt
-a---         3/28/2016   2:07 AM          0 00012_asdfasdfsa df - Copy (3).txt
-a---         3/28/2016   2:07 AM          0 00013_asdfasdfsa df - Copy.txt
-a---         3/28/2016   2:07 AM          0 00014_asdfasdfsa df - Copy (6).txt
-a---         3/28/2016   2:07 AM          0 00015_asdfasdfsa df - Copy (5).txt
-a---         3/28/2016   2:07 AM          0 00016_asdfasdfsa df - Copy (4).txt
-a---         3/28/2016   2:07 AM          0 00017_asdfasdfsa df - Copy (2).txt
-a---         3/28/2016   2:07 AM          0 700006_asdfasdfsa df - Copy (4) - Copy.txt


PS S:\temp&gt;
</code></pre>

<p>Now my PowerShell code is:</p>

<pre><code>dir * | ?{$_.name -match '^\d{5}_.+'} | Rename-Item -NewName {$_.name -replace '^(\d{5})(_.+)', ((([convert]::ToInt32('$1', 10) + 12).ToString("00000")) + '$2')} -whatif
</code></pre>

<p>I can't find any errors in my code. But when I run it, I got the following error message:</p>

<pre><code>Rename-Item : The input to the script block for parameter 'NewName' failed. Exception calling "ToInt32" with "2" argument(s): "Could not find any recognizable digits."
At line:1 char:62
+ dir * | ?{$_.name -match '^\d{5}_.+'} | Rename-Item -NewName {$_.name -replace ' ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (S:\temp\00001_asdfasdfsa df.txt:PSObject) [Rename-Item], ParameterBindingException
    + FullyQualifiedErrorId : ScriptBlockArgumentInvocationFailed,Microsoft.PowerShell.Commands.RenameItemCommand
</code></pre>

<p>My question is, where I am wrong? Is it because I should not use functions in the replacement part of the <code>replace</code> operator? If so, how to write complex logic in <code>-newname{}</code>? Thanks.</p>