Question

I want to turn off the Global setting (as it is set default to be used on .NET) as what I am trying to do only needs to change the first part of a string, however there is the the chance that it will occur twice in the string, for example I wish for

C00000WPF0000SAND

to only change the first instance of 0’s.

if (Regex.IsMatch(text, "^[a-z]+00+", RegexOptions.IgnoreCase))
{
    text = Regex.Replace(text, "0{1,}", "00*", RegexOptions.IgnoreCase);
}

This is how I am currently doing it, however this seems to take every single instance of the “00+” and change it but this messes things up.

Answer 1

You need to specify a match limit; the documentation for Regex.Replace(string, string, RegexOptions) specifically states that it replaces all instances of the found pattern. There is no static overload of Regex.Replace that takes both a match limit and regex options, so you will have to construct a Regex object and then use the Replace(string, string, int) overload. Try this:

text = new Regex("0{1,}", RegexOptions.IgnoreCase).Replace(text, "00*", 1);