Friday Fun What a CHAR!

Last week I posted a PowerShell snippet on Twitter. My original post piped an array of integers as [CHAR] type using an OFS. Don’t worry about that. As many people reminded me, it is much easier to use the -Join operator.

I’ll let you try that on your own. The [CHAR] type is used to represent a character as an integer value, like this:

For this week’s Friday Fun I thought it would be nice to translate a string of text into corresponding character values. It looks like a secret code! Or we could use the translation in a join scriptblock. So I put together a little script I call Translate-ToChar.ps1. The script takes a string of text and writes an array of [CHAR] objects.

The script begins by defining a map hash table for what I think are all characters you are likely to find on a US keyboard. These should be character values 33 through 125 which I get using the range (..) operator.

Each number is piped to ForEach object where I add it to the hash table. In order to get the hash table key to work properly I cast the number as a string and the hash table value is the same number cast as a [CHAR]. Now we can begin breaking the string apart and “translating” it.

The script splits the string into a character array using the default delimiter of a space. Because I’m going to be using a pipelined expression, I save the current letter as a variable. It will keep things straight in a moment.

The next step is to find the character in the hash table values. I found the best way to accomplish this was to call the hash table’s GetEnumerator() method. This way I can pipe it to Where-Object and find the corresponding key.

Notice I’m using the case sensitive -ceq operator. The Name property of the hash table enumerator is the key value, or in other words the corresponding [CHAR] integer. With me still? This value is added to an array for the final result. In fact the default isĀ to simply write $values to the pipeline. But, I’ve included a -Scriptblock parameter to have the script write a scriptblock to the pipeline using the -Join operator I mentioned earlier. Now for the interesting part.

I have an array variable which needs to be expanded into the scriptblock. This won’t work:

I’ll end up with a scriptblock but have no way of resolving $values once the script ends. So instead I create a string with $values knowing that PowerShell will expand it. And because I want the array to be expanded as a comma separated string, I’ll specify the $ofs variable as a comma. The default is a space.

The variable $t is now a string with all of the integer values from $values as a comma separated list. I can turn this into scriptblock like this:

The scriptblock gets written to the pipeline. So, I could run the script like this:

Now I can use $a however I want. Or I could create a scriptblock.

I can invoke $b anytime I want to see the message.

While I don’t expect you to be running this in production I hope you picked up some tips on using hash tables, arrays, scriptblocks and casting variable types.

Download Translate-ToChar

The PowerShell Day Care: Building ScriptBlocks

Good morning kids and welcome to the PowerShell Day Care center. We offer a creative and nurturing environment for PowerShell professionals of all ages. Later there might even be juice and cookies. But first let’s get out our blocks, our scriptblocks, and start building. I’ve written a number of posts on script blocks and today have a script to offer, that even if you don’t need it as is, it might offer a few insights into PowerShell. Continue reading

Get Properties with Values

One of my nuisance issues when using WMI with Windows PowerShell, is that when looking at all properties I have to wade though many that have no value. I’d prefer to only view properties that have a populated value. Here’s one way. Continue reading

ScriptBlocks On the Fly

I’m always preaching about writing PowerShell scripts and functions with reuse and modularization in mind. You should never have to write the same block of code twice. But what about in the shell during your daily grind? Perhaps today you’re dealing with some issue and periodically need to run a particular block of code. Now, you could run it once, make a note of the command number and then use Invoke-History throughout the day to keep running it. What I like to do in these situations is create a scriptblock which is assigned to a variable. Then I can invoke it anytime I want. Continue reading

Friday Fun: Start-TypedDemo v2

Not too long ago I posted a function I wrote for doing PowerShell demonstrations. My goal was to simulate a live interactive demo but without the typing so I could focus on explaining and not typing. The first version was a good start but I always had plans for a more feature complete function including typos, support for multiline expressions and transcription. That’s what I have for today’s Friday Fun. Continue reading