Powershell-如何使用点星号将变量传递给选择字符串中的正则表达式

Question

Basically i have a text file and i'm trying to grep (select-string) each line for the regex combination

VariableA.*VariableB

This should output any line that looks something like:

xxxxxVariableAxxxxxxxxxVariableBxxxx

And when i do it like this it works:

select-string "11568.*19521" d:\sourcefiledir\sourcefile.csv  | select -exp line | Out-File c:\destfiledir\destfile.csv -Append

What i want to do is pass variables into the regex. So i defined two arrays

$ArrayA = @(23423, 45435, 234142, 24532)
$ArrayB = @(23423, 23423, 23424, 2342429)

and then do a for loop over the array slotting in the variables. But i cant's get it work. I've tried the following:

select-string -Path D:\somelocation\somefile.csv -Pattern "$ArrayA[j].*$ArrayB[j]" | select -exp line | Out-File c:\somepath\somefile.csv

or without using the Pattern/Path switches

select-string "$ArrayA[j].*$ArrayB[j]" D:\somelocation\somefile.csv | select -exp line | Out-File c:\somepath\somefile.csv

or with single quotes

select-string '$ArrayA[j].*$ArrayB[j]' D:\somelocation\somefile.csv | select -exp line | Out-File c:\somepath\somefile.csv

or trying to define it as a regex variable

[regex] $regstring = "$ArrayA[j].*$ArrayB[j]"
select-string $regstring D:\somelocation\somefile.csv | select -exp line | Out-File c:\somepath\somefile.csv

or

select-string -Path D:\somelocation\somefile.csv -Pattern $regstring | select -exp line | Out-File c:\somepath\somefile.csv

Basically i think it doesn't pass the variables through correctly to the select-string.. but i can't work out what the problem is

Answer 1

To embed complex expressions use a sub-expression inside the string: $(...)

$str = "$($ArrayA[j]).*$($ArrayB[j])"

A sub-expression can basically be an entire set of things to be executed:

$str = "Blah $((Get-Process | Select-Object -ExpandProperty Name) -join '~') bleh"

You can use the format operator as well:

$str = "{0}.*{1}" -f $ArrayA[j],$ArrayB[j]

Or pre-create a variable and embed that:

$aAj = $ArrayA[j]
$aBj = $ArrayB[j]
$str = "$aAj.*$aBj"