Cannot convert the "System.Char[,]" value of type "System.Char[,]" to type &quot-CodePudding

I've got simple script, which creates 2d char array, and invokes function, which should to fill that array with given char.

[int]$size = Read-Host "Please, enter the board size"

$playerBoard = New-Object 'char[,]' $size,$size

Fill-Boad-With-Symbol($playerBoard,'*',$size)

and here is the function


function   Fill-Boad-With-Symbol([char[,]]$board, [char]$symbol,[int]$boardSize){
    for ($i=0; $i -lt $boardSize; $i  ) {
        for ($j=0; $j -lt $boardSize; $j  ) {
            $board[$i,$j] = $symbol
        }
    }
}

But when executing this code i get the following error:

  Cannot process argument transformation on parameter 'board'. Cannot convert the "System.Char[,]" value of type "System.Char[,]" to type "System.Char"
...
  Fill-Boad-With-Symbol($playerBoard,'*',$size)

I kindly ask to explain, what am I doing wrong?

CodePudding user response：

As in my comment, in PowerShell, arguments are either positional or named, your first error is the way you're passing arguments to your function. By doing this:

Fill-Board-Symbol($playerBoard,'*',$size)

PowerShell will interpret it as if you were passing an object[] (object array) which 1st element array[0] will be the $playerBoard, 2nd element would be a * and 3rd element, an int to the first parameter of your function -Board which is type constraint to char[,].

PowerShell will then attempt type conversion from object[] to char[,] and it will fail with that exception you see.

Example:

Given these variables:

$playerBoard = New-Object 'char[,]' 2,2
$symbol = '*'
$size = 2

Grouping them together (...) we can inspect it's type:

PS /> ($playerBoard, $symbol, $size).GetType()

IsPublic IsSerial Name         BaseType
-------- -------- ----         --------
True     True     Object[]     System.Array

If we attempt to convert it to [char[,]]:

PS /> [char[,]]($playerBoard, $symbol, $size)

InvalidArgument: Cannot convert the "System.Char[,]" value of type "System.Char[,]" to type "System.Char".

Try doing this instead:

[int]$size = Read-Host "Please, enter the board size"
$playerBoard = New-Object 'char[,]' $size,$size

function Fill-Board-With-Symbol {
param(
    [char[,]]$board,
    [char]$symbol,
    [int]$boardSize
)
    for ($i=0; $i -lt $boardSize; $i  ) {
        for ($j=0; $j -lt $boardSize; $j  ) {
            $board[$i,$j] = $symbol
        }
    }
    $board # => This is your output
}

$newBoard = Fill-Board-With-Symbol -Board $playerBoard -Symbol '*' -BoardSize $size
$newBoard