Find indexof array of objects

Question

When working with an array of values, indexof can be used to find the position of the value in the array.

#this returns '1', correctly identifying 'blue' in position '1' of the array
$valueArray = @('cup','blue','orange','bicycle')
[array]::indexof($valueArray,'blue')

I would like to use this command to find the position of a file (image) in an array of objects generated with Get-ChildItem, however the returned position is always '-1' no matter where the object I have called for actually is. Note that image123.jpg is in the middle of the array.

$imageArray = Get-ChildItem "C:\Images"
[array]::indexof($imageArray,'image123.jpg')

I have noticed that if I change the array to filenames only, it works returning the actual position of the filename.

$imageArray = Get-ChildItem "C:\Images" | select -expand Name
[array]::indexof($imagesToReview,'image123.jpg')

Is this just the nature of using indexof or is there a way to find the correct position of the image file in the array without converting?

Answer 1

The easiest solution here is the following:

$imageArray = Get-ChildItem "C:\Images"
[array]::indexof($imageArray.Name,'image123.jpg')

Explanation:

[array]::IndexOf(array array,System.Object value) searches an array object for an object value. If no match is found, it returns the array lower bound minus 1. Since the array's first index is 0, then it returns the result of 0-1.

Get-ChildItem -Path SomePath returns an array of DirectoryInfo and FileInfo objects. Each of those objects has various properties and values. Just using $imageArray to compare to image123.jpg would be comparing a System.IO.FileInfo object to a String object. PowerShell won't automatically convert a FileInfo object into a string while correctly parsing to find your target value.

When you choose to select a property value of each object in the array, you are returning an array of those property values only. Using $imageArray | Select -Expand Name and $imageArray.Name return an array of Name property values. Name contains a string in your example. This means you are comparing a String to a String when using [array]::IndexOf($imageArray.Name,'image123.jpg').