如何用正则表达式替换字符串？

Question

I replace my string as below;

string str = "Opps V 14";
str = str.Replace("V 14", "V14");

But numeric part of string is not static. Sometimes it can be "V 17", "V 13" etc..

How can I replace that with regular expressions globally?

Answer 1

This will replace the space between V and a digit with nothing:

string pattern = @"(?<=\bV) (?=\d)";
Regex rgx = new Regex(pattern);
string result = rgx.Replace(str, "");

(?<=\\bV) is a lookbehind assertion and means "preceded by V", \\b is a word boundary.

(?=\\d) is a lookahead assertion and means "followed by a digit"

Lookaround assertions are not part of the match result but only checks. This is the reason why only the space is removed.

note: you must include using System.Text.RegularExpressions; at the begining of the file.

Answer 2

Assuming that except the number, rest of the string is static, then its as simple as removing the space after V:

str = str.Replace("V ","V");

Answer 3

class Program
{
    static void Main(string[] args)
    {
        string str = "Opps V 14";
        string[] temp = str.Split(' ');
        str = String.Join(" ", temp.Take(2)) + temp.Last();
    }
}