Powershell can't invoke .net class' method

Question

I wrote powershell script which contains this code:
foreach ($line in [System.IO.File]::ReadLines ...
It works fine on my pc but fails on another one (the same .net framework version) with error: Method invocation failed because [System.IO.File] doesn't contain a method named 'ReadLines'. What's wrong?

First example says ReadLine... your error says ReadLines with an S. Is that a typo or the cause ? — Knuckle-Dragger
– Knuckle-Dragger, Commented Mar 21, 2014 at 8:26
@Knuckle-Dragger sorry, it's ReadLines. I've corrected this. — Maxim Tkachenko
– Maxim Tkachenko, Commented Mar 21, 2014 at 8:36

Peter Reavy · Accepted Answer · 2014-03-21 11:13:08Z

2

Unless you have a strong reason to use [System.IO.File]::ReadLines, consider PowerShell's Get-Content cmdlet instead:

foreach ($line in Get-Content .\my\file.txt)
{
   Write-Output $line
}

Also, foreach is an alias for ForEach-Object and you can pipe to it. Each object in the pipeline is referred to as $_. So you can write a script block which will run for every line in your file like this:

Get-Content .\my\file.txt | { Write-Output $_ }

answered Mar 21, 2014 at 11:13

Peter Reavy

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CB. · Accepted Answer · 2014-03-21 11:14:31Z

1

Are you sure that all involved computers are with .net 4.0 installed? And that Powershell is version 3.0 or at least 2.0 with powershell.exe.config customized to use .Net 4.0 ?

File.ReadLines starts only from .Net 4.0.

Why not use get-content cmdlet?

answered Mar 21, 2014 at 11:14

CB.

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1 Comment

Maxim Tkachenko Over a year ago

My solution with ReadLines works fine on my pc (Windows 8), another pc has installed Windows7.

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