How to delete a string from a text file?

Question

I currently have two strings assigned - domain,subdomain

How could I delete any matched occurrences of these strings in a text file?

string domain = "127.0.0.1 test.com"
string subdomain = "127.0.0.1 sub.test.com"

I don't think using a regex would be ideal in this situation.

How can this be done?

Answer 1

You need to:

• Open the existing file for input
• Open a new file for output
• Repeatedly:
  • Read a line of text from the input
  • See if it matches your pattern (it's unclear at the moment what pattern you're looking for)
  • If it doesn't , write the line to the output (or if you're only trying to remove bits of lines, work out which bit you want to write out)
• Close both the input and output (a using statement will do this automatically)
• Optionally delete the original file and rename the new one if you want to effectively replace the original.

Answer 2

var result = Regex.Replace(File.ReadAllText("file.txt"),
    @"127\.0\.0\.1 test\.com|127\.0\.0\.1 sub\.test\.com", string.Empty);

Then write to file obtained result.