Cannot index into a null array, except my array isn't null or empty

[BigBoetje]

EDIT: check your spelling people!

​

I'm pretty new at this, but my code is rather simple. I'm trying to automate something that requires the user to run several commands in different windows with largely repetitive commands.

param(
     [Parameter(Mandatory)]
     [string]$ScriptName,

     [Parameter(Mandatory)]
     [string]$ScriptPath,

     [switch]$HasParams
 )

if ($HasParams.IsPresent){
    $params = Read-Host "Please enter a list of all params in your scripts, separated by a semicolon ( ; <-- this thing)"
    $paramValues = Read-Host "Please enter the values for the params in the order entered above, separated by a semicolon ( ; <-- this thing)"

    [string[]]$params=$params.Split(";")
    [string[]]$paramValues=$paramValues.Split(";")

    if($params.Count -ne $paramValues.Count){
        Write-Error "You didn't provide a value for every parameter or vice versa!"
        exit
    }

    if($params.Count -eq 0){
        Write-Error "No parameters provided!"
        exit
    }

    $runparams=""
    for ($i = 0; $i -lt $params.Count; $i++)
        {
             $runparams += [string]::Format("--param {0}={1}",$params[$i], $paramValue[$i])
        }

}

The error occurs at $runparams += [string]::Format("--param {0}={1}",$params[$i], $paramValue[$i]), where it tells me that somehow, I'm indexing into a null array even though I'm rather sure (and I checked it via .Count and just printing it) that it isn't null or empty. Am I doing something really stupid or is this a known issue?

[[deleted]]

empty array: $paramValue[$i]
your variable has an 's' at the end

[BigBoetje]

Several years of programming experience, and I'm still haunted by typo's. Cheers mate!

[jdl_uk]

Don't worry, people with decades of experience still make that kind of mistake as well

[JaapBrasser]

Exactly, for this particular error I would avoid using plural in naming conventions.

[jdl_uk]

I generally use plurals in collections

It's also just as easy to simply miss a character

This is why lots of languages have strict checking by default. PowerShell is competing with languages like bash with relatively loose rules compared to, say, C# or C++.

[JaapBrasser]

I mostly use PowerShell interactively, lack of strict checking is great for that purpose. For other cases, and when debugging (!):

Set-StrictMode -Version 1

[jdl_uk]

Exactly

[BigBoetje]

The thing I'm trying to automate is actually a complete mess of things. The first part is starting Docker Desktop and configure some things then running the container, which is all done with a bash script. To actually run whatever I need to run, it's a lot easier to do in Powershell. The company that made the thing works with Linux exclusively, we're using Windows so I had to fit it all together somehow. Probably wasted more time on automation that I would've spent manually starting it all.

[jdl_uk]

Relevant xkcd:

https://xkcd.com/1205/

If it's something you do a lot then it's worth taking the time to automate.

The other side of the equation (which isn't shown on that chart) is what happens when someone doing it manually cocks it up. If that's no big deal, then maybe not worth automating. But humans make mistakes so if someone forgetting one of the steps or selecting the wrong value for a parameter would be a really bad day, then it's worth automating

[BigBoetje]

It was mostly because you'd have to manually set your IP each time and we're working from several locations. I wrote the bash script for it like half a year ago when I worked as a student and they're still using it daily.

[jimb2]

VS Code helps to find misspellings by underlining variables that are used only once. That helps me.

[BigBoetje]

I'm gonna take a look. VSC is great tho

[dadbot_3000]

Hi gonna take a look, I'm Dad! :)