How to remove and place a single character in a string?

Question

Here's my string: String s = "X0001";

Now I want to replace X with N.

i.e String s = "N0001;

How can I do this?

Answer 1

You can use Replace:

String s = "X0001";
s = s.Replace('X', 'N');

With this, Console.WriteLine(s) will output

N0001

Answer 2

If you want to replace all, use String.Replace:

s = s.Replace("X", "N");

If you want to replace the first;

s = "N" + s.Substring(1);

If you have something like <xml><Name>X0001</Name> and you want to replace X0001 with N0001 you can use string methods ( or XML libraries):

string xml = "<xml><Name>X0001</Name>";
int start = xml.IndexOf("<Name>", StringComparison.InvariantCultureIgnoreCase);
if (start >= 0)
{
    start += "<Name>".Length;
    int end = xml.IndexOf("</Name>", start, StringComparison.InvariantCultureIgnoreCase);
    if (end >= 0)
    {
        string before = xml.Substring(0, start);
        string token = xml.Substring(start, end - start);
        string after = xml.Substring(end);
        if (token.Length > 0)
            xml = string.Format("{0}{1}{2}", 
                before, 
                token.Replace("X", "N"), 
                after);
    }
}