String Replace

[J-Deezy]

Try this

Regex.Replace(sHTMLstream, "\bvb\b", "C#", RegexOptions.IgnoreCase)

I just tested it and it worked aok.

The reason yours didn't work was because of your pattern.

pattern = "\\bvb\b"

you put two slashes before the first wordboundary, a double slash is when you wish to include a slash literal (i.e your match will contain a "\" so you don't want the metacharacter) In effect, the pattern YOUR RegEx was looking for was the literal: "\bvb", which isn't what you want.