static void Main()
{
string path = @"D:\GITHUB\C#\222.txt";
string s = File.ReadAllText(path);
bool toUp = false;
foreach(var c in path)
{
if(c == '\"') { toUp = !toUp; continue; }
s.Append(toUp ? char.ToUpper(c) : c);
}
string appendText = s;
File.WriteAllText(path, s);
}