存储在PowerShell中的变量中的字符串出现意外行为

Question

I'm getting some odd behavior from Excel's Cells.Find() method:

Variable I'm searching on:

PS > $volumename
vol_01       

PS > $volumename.GetType()

IsPublic IsSerial Name                                     BaseType                                                                                                                                            
-------- -------- ----                                     --------                                                                                                                                            
True     True     String                                   System.Object 

produces no results:

PS > $sheet.Cells.Find($volumename).Row

but if I manually copy and paste the value of that variable:

PS > $volumename = "vol_01"
PS > $volumename.GetType()

IsPublic IsSerial Name                                     BaseType                                                                                                                                            
-------- -------- ----                                     --------                                                                                                                                            
True     True     String                                   System.Object 

Gets the value I am expecting:

PS > $sheet.Cells.Find($volumename).Row
198

They appear to be exactly the same type in every way to me. This doesn't happen for every case. Some volume names passthrough fine while others do not. I did scrub the volume name for this post as it has a customers naming convention. It is the same format as above and the same format as the volume names that work.

Answer 1

The following snippet can be used to inspect a string for hidden control characters :

PS> & { [int[]] [char[]] $Args[0] | % { '0x{0:x} [{1}]' -f $_, [char] $_ } } "vol_01`n"
0x76 [v]
0x6f [o]
0x6c [l]
0x5f [_]
0x30 [0]
0x31 [1]
0xa [
]

The first column is each character's Unicode code point ("ASCII code"), and the second column the character itself, enclosed in [...]

Note that I've added "`n" at the end of the string - a newline character ( U+000A ) - whose code point expressed as a hex. number is 0xa .

If, as in your case, the only unwanted part of the string is trailing whitespace , you can remove them as follows:

$volumename.TrimEnd() # trim trailing whitespace

In your case, the trailing whitespace is 0xa0 , the NO-BREAK SPACE ( U+00A0 ) , which .TrimEnd() also removes, as Tom Blodget points out.

---

Simple function wrapper based on the above, for use with pipeline input:

filter debug-Chars { [int[]] [char[]] $_ | % { '0x{0:x} [{1}]' -f $_, [char] $_ } }

Sample use:

"vol_01`n" | debug-Chars