Get the nth string of text between 2 separator characters

Question

I have a long string of text delimited by a character (pipe character). I need to get the text between the 3rd and 4th pipes. Not sure how to go about this...

Open to regex or non-regex, whichever is the most efficient. Especially open to extension method if none exist to be able to pass in:

seperatorChar
index

Couldn't you just indexOf with a start index of the previous pipe until you get to 3rd then substring to the index of the 4th pipe(starting from the index of the 3rd) ? Or just use string split on pipe :P — Brian Colvin, Sep 21 '11 at 16:34
This indexOf suggestion would be the fastest by far, I would think, because it's not creating a bunch of separate strings (and an array!) that you don't need. All of the other solutions here create a lot of unneeded objects. — Joe Strout, Mar 30 '16 at 18:29

Dour High Arch · Accepted Answer · 2011-09-21T17:05:52.363

7

If

string textBetween3rdAnd4thPipe = "zero|one|two|three|four".Split('|')[3];

doesn't do what you mean, you need to explain in more detail.

edited Sep 21 '11 at 17:05

answered Sep 21 '11 at 16:41

Dour High Arch

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2

I would choose this answer over a regex. – Christopher Currens Sep 21 '11 at 16:43

score 2 · Answer 2 · answered Sep 21 '11 at 16:42

2

This regex will store the text between the 3rd and 4th | you want in $1

/(?:([^|]*)|){4}/


Regex r = new Regex(@"(?:([^|]*)|){4}");
r.match(string);
Match m = r.Match(text);
trace(m.Groups[1].captures);

answered Sep 21 '11 at 16:42

Jacob Eggers

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score 2 · Answer 3 · answered Sep 21 '11 at 16:44

Try This

public String GetSubString(this String originalStirng, StringString delimiter,Int32 Index)
{
   String output = originalStirng.Split(delimiter);
   try
   {
      return output[Index];
   }
   catch(OutOfIndexException ex)
   {
      return String.Empty;
   }
}

score 1 · Answer 4 · answered Mar 30 '16 at 18:52

Here's my solution, which I expect to be more efficient than the others because it's not creating a bunch of strings and an array that are not needed.

/// <summary>
/// Get the Nth field of a string, where fields are delimited by some substring.
/// </summary>
/// <param name="str">string to search in</param>
/// <param name="index">0-based index of field to get</param>
/// <param name="separator">separator substring</param>
/// <returns>Nth field, or null if out of bounds</returns>
public static string NthField(this string str, int index, string separator=" ") {
    int count = 0;
    int startPos = 0;
    while (startPos < str.Length) {
        int endPos = str.IndexOf(separator, startPos);
        if (endPos < 0) endPos = str.Length;
        if (count == index) return str.Substring(startPos, endPos-startPos);
        count++;
        startPos = endPos + separator.Length;
    }
    return null;
}

only slightly unusual behavior of this implementation is that if the separator is not found, the entire search string is returned, that is "abc" & "|abc|" (if using pipes as per op) will both return "abc". — Brent, Apr 30 '17 at 11:03
For what index? NthField("abc", 0, "|") certainly returns "abc", but NthField("|abc|", 0, "") should return empty string, because it starts with a delimiter. And as for field 1, NthField("abc", 1, "|"), that returns null (while for "|abc|" it returns "abc"). All as it should be, I think. Or have I missed something? — Joe Strout, May 01 '17 at 14:07

score 1 · Answer 5 · answered Sep 21 '11 at 16:54

1

You could do

     string text = str.Split('|')[3];

where str is your long string.

answered Sep 21 '11 at 16:54

rohit89

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Get the nth string of text between 2 separator characters

5 Answers5

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