Question

I want to replace text from a certain range in my HTML file (like from position 1000 to 200000) with text from another HTML file. Can someone recommend me the best way to do this?

Answer 1

Try this:

string input = File.ReadAllText("<< input HTML file >>");
string replacement = File.ReadAllText("<< replacement HTML file >>");

int startIndex = 1000;
int endIndex = 200000;

var sb = new StringBuilder(
    input.Length - (endIndex - startIndex) + replacement.Length
);

sb.Append(input.Substring(0, startIndex));
sb.Append(replacement);
sb.Append(input.Substring(endIndex));

string output = sb.ToString();