Is there a simple implementation to test whether all elements of an array are exactly the same?-CodePudding

I need to determine whether all elements of an array are exactly the same. I'd like this to play nice with all data-types as well, Object/String/Int/etc.

Is there an easy way to do this in PowerShell?

function Test-ArrayElementsEqual {
    [CmdletBinding()]
    param (
        [Parameter(Mandatory,Position = 0,ValueFromPipeline)]
        [object]
        $Array,
    )

    $test = $null
    foreach ($item in $Array) {
        if(!$test){
            $test = $item
            continue
        }
        if($test -ne $item){
            return $false
        }
    }
    return $true
}

This is what I have now, but I have a feeling it's a broken implementation, and that there is something more elegant.

Any help would be great.

CodePudding user response：

As in my comment, for simple comparisons you can use what Lee_Dailey proposed in his comment only adding a type comparison which can be accomplished by the use of .GetType() method.

This function will return $true if all elements are of the same type and same value and will return the index and expected value / type of the first element that is not of the same type or does not have the same value.

function Test-ArrayElementsEqual {
[CmdletBinding()]
param (
    [Parameter(Mandatory)]
    $InputObject
)
    begin
    {
        $refVal = $InputObject[0]
        $refType = $refVal.GetType()
        $index = 0
    }

    process
    {
        foreach($element in $InputObject)
        {
            if($element -isnot $refType)
            {
                "Different Type at Position $index. Expected Type was {0}." -f $refType.FullName
                return
            }
            if($element -ne $refVal)
            {
                "Different Value at Position $index. Expected Value was $refVal."
                return
            }

            $index  
        }

        $true
    }
}

Test Examples

$arr1 = 123, 123, '123'
$arr2 = 123, 345, 123
$arr3 = 'test', 'test', 'test'

Results

PS /> Test-ArrayElementsEqual $arr1
Different Type at Position 2. Expected Type was System.Int32.

PS /> Test-ArrayElementsEqual $arr2
Different Value at Position 1. Expected Value was 123.

PS /> Test-ArrayElementsEqual $arr3
True

If you're looking for a way of comparing if different objects are the same you might find useful information on the answers of this question: Prevent adding pscustomobject to array if already exists