How can I put an escape character in front of special characters using C #?

Question

buildLetter.Append("</head>").AppendLine();
buildLetter.Append("").AppendLine();
buildLetter.Append("<style type="text/css">").AppendLine();

Suppose the above content is in a file. I want to write a fragment that deletes any line with the empty string "" and places the escape character in front of the middle quotes. The end result will be:

buildLetter.Append("</head>").AppendLine();
buildLetter.Append("<style type=\"text/css\">").AppendLine();

External "...." are not considered special characters. Special characters can be single quote or double quotation mark.

I could run it through the Visual Studio search and replace function. However, in my case i want it to be written in C # or VB.NET

Any help would be appreciated.

Answer 1

, , :

string s = File.ReadAllText("input.txt");
string empty = "buildLetter.Append(\"\").AppendLine();" + Environment.NewLine;
s = s.Replace(empty, "");
s = Regex.Replace(s, @"(?<="").*(?="")",
         match => { return match.Value.Replace("\"",  "\\\""); }
    );

:

buildLetter.Append("</head>").AppendLine();
buildLetter.Append("<style type=\"text/css\">").AppendLine();