正则表达式将数字替换为2 *数字-1。用于替换文件名

public string CalculateNumber(Match match)
{
    int i = Convert.ToInt32(match.Value);
    i = i * 2 - 1;
    return i.ToString();
}

String fileName = "filename23.pdf";
fileName = Regex.Replace(fileName, @"d+", CalculateNumber);

i*2-1

checked

BigInteger

#!/usr/bin/perl
use 5.10.1;
use strict;
use warnings;

my $in = 'filename225.pdf';
$in =~ s/(d+)/$1*2-1/e;
say $in;

filename449.pdf

function compute($matches) {
    return $matches[1]*2-1;
}
$in = 'filename225.pdf';
$res = preg_replace_callback('/(d+)/',"compute", $in);;
echo $res,"n";