C# Replace parts of String in txt file

Question

Hello.

I’m studying C# and I’m struggling with a function.

I have an array, like below, where each node contains an id, a Pattern(regex) and a value for replacing the part of the string that matches that value.

I load the contents of the txt file into contenFile and if, for example, you match some part of the contenFile, you replace the match with "ABC" and so with the other positions of the array. If no match, enter the value at the end.

The file contains fields to match and not match

< tag 101" > < tag2 >BBBBBBBBBBB< /tag2 > < tag4 >CCCCCC< /tag4 > < tag 101" >

If anyone can help or indicate any content for study, please.

At the moment the code is like this:

public void Edit()
{
string[,] items = {{"001", "<tag ([0-9]{3})\">", "ABC"},
                    {"002", "<tag2>.+</tag2>", "DEF"},
                    {"", "<tag3>.+</tag3>", "GHI"}};
try
{
using (StreamReader sr = new StreamReader(@"C:\test.xml"))
{
string contentFile = sr.ReadToEnd();

foreach (string entry in items)
{
if (!Regex.IsMatch(contentFile, entry[1].ToString()))
{
contentFile = contentFile.Insert(contentFile.Length, entry[2].ToString());
}
else
{
contentFile = Regex.Replace(contentFile, entry[1].ToString(), entry[2].ToString());
}
}
}
}
catch (Exception ex)
{
}
}