Is there an option “go to line” in TextReader/StreamReader?

Question

I have a huge text file with 25k lines.Inside that text file each line starts with \"1 \\t (linenumber)\"

Example:

1   1   ITEM_ETC_GOLD_01    골드(소)          


        

Answer 1

If you are dealing with a fixed-width data format (ie. you know all the lines to be the same length), you can multiply the length with your desired line number and use Stream.Seek to find the start point of the nth line.

If the lines are not fixed length, you need to find the right number of line breaks until you are at the beginning of the line you want. That would be easiest done with StreamReader.ReadLine. (You can make an extension method to make the file en IEnumerable as Jon Skeet suggests - this would get you nicer syntax, but under the hood you will be using ReadLine).

If performance is an issue, it might be (a little bit) more efficient to scan for byte sequences in the file manually using the Stream.Read method. I haven't tested that; but the StreamReader obviously need to do some work to construct a string out of the byte sequence - if you don't care about the first lines, this work can be saved, so theoretically you should be able to make a scanning method that performs better. This would be a lot more work for you, however.