Case insensitive Regex Relpace

Case insensitive Regex Relpace:

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string source = "Hello India"; string expr = @"\b" + Regex.Escape("Hello") + @"\b"; source = Regex.Replace(source, expr, m => {     return "World"; }, RegexOptions.IgnoreCase); Console.WriteLine(source);

Replaces the word "Hello"|"hello"|"hELLO" with the word "World"