Why does a subexpression of $(Write-Host) output to beginning of string?

Question

Using Write-Host in a $() subexpression always outputs to the beginning of a string, regardless of its position.

For example:

"This is $(Write-Host 'now at the beginning' -NoNewline)"

Outputs:

now at the beginningThis is

Other cmdlets work as expected here (e.g. "Today is $((Get-Date).DayOfWeek)", Today is Friday).

How is Write-Host different?

TessellatingHeckler · Accepted Answer · 2016-10-01 04:14:00Z

3

It doesn't "output to the beginning of the string", it writes to the host twice, in 'backwards' order.

"abc $()" is a string literal that includes a sub-expression.
Calculating what the string is, means evaluating the $()
Evaluating the $() writes to the screen now at the beginning and returns nothing
Now the string literal is "abc"
Now "abc" is written to the screen now at the beginningabc

This is not doing what you suggest:

answered Oct 1, 2016 at 4:14

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