How to change the value of XML Element attribute using PowerShell?

I am trying to access and change the particular attribute from XML tag

XML:

<office>
<staff branch="Hanover" Type="sales">
<employee>
<Name>Tobias Weltner</Name>
<function>management</function>
<age>39</age>
</employee>
<employee>
<Name>Cofi Heidecke</Name>
<function>security</function>
<age>4</age>
</employee>
</staff>
<staff branch="London" Type="Technology">
<employee>
<Name>XXXX</Name>
<function>gement</function>
<age>39</age>

From the above example I want to print <staff> branch attribute and then want to change it with one value such as New York in all the whole XML and using below code to do that

$xml=New-Object XML

$xml.Load("C:\FE6Work.xml")

$node=$xml.SelectNodes("/office/staff")

write-output $node.branch
$node.branch="New York"

But get an error stating can't find the element.

Can someone please help?

You can access the attributes directly in the `[xml]` object like this:

# C:\temp> $xml = [xml](Get-Content C:\FE6Work.xml)
# C:\temp> $xml.office.staff

branch Type employee
------ ---- --------
Hanover sales {Tobias Weltner, Cofi Heidecke}
London Technology {XXXX, Cofi}

# C:\temp> $xml.office.staff | foreach{$_.branch = "New York"}
# C:\temp> $xml.office.staff

branch Type employee
------ ---- --------
New York sales {Tobias Weltner, Cofi Heidecke}
New York Technology {XXXX, Cofi}

Try the following:

$nodes = $xml.SelectNodes("/office/staff");
foreach($node in $nodes) {
$node.SetAttribute("branch", "New York");
}

This will iterate through all nodes returned by SelectNodes() and modify each one.

if we are taking attribute from console and changing its value ?

$path=Read-Host -Prompt 'Enter path of xml file'
[xml]$xmldata = get-content "$path"

$tag = Read-Host -Prompt 'Enter tag'
$value = Read-Host -Prompt 'Enter value'
$xmldata.InstallConfig.$tag="$value"
$xmldata.Save($path)