Powershell Extract Number from File Name

问题

Files names could be:

1234_billing.txt
1234billling.txt
123_billing.txt
123billing.txt

How can I extract the only the number in all 4 cases? I've tried -split and $_.BaseName.Substring() but can't seem to get it correct.

回答1:

Assuming that the filenames are in the array variable $flist, the following will do the trick:

foreach ($file in $flist) {
    if ($file -match "\d+") {
        $matches.value
    }
}

The -match operator takes as its right operand a regex pattern; in this case we use the pattern \d+ to signal any non-zero number of consecutive digits. The operator returns either $true or $false, and stores the matched substring in $matches. There's more about the -match operator at Get-Help about_Operators, and everyone can use a handy reference for regular expressions.

来源：https://stackoverflow.com/questions/48409026/powershell-extract-number-from-file-name