如何使用Split（）重构此C＃代码？

Question

How can I refactor this so that numberOfItems doesn't have to be declared as a variable?

//method: gets the text in a string in front of a marker, if marker is not there, then return empty string
//example: GetTextAfterMarker("documents/jan/letter043.doc","/") returns "letter043.doc"
//example: GetTextAfterMarker("letter043.doc","/") returns ""
//example: GetTextAfterMarker("letter043.doc",".") returns "doc"
public static string GetTextAfterMarker(string line, string marker)
{
    int numberOfItems = line.Split(new string[] { marker }, StringSplitOptions.None).Count();

    string result = line.Split(new string[] { marker }, StringSplitOptions.None)[numberOfItems-1];
    return line.Equals(result) ? string.Empty : result;
}

Answer 1

var    index = line.LastIndexOf (marker) ;
return index < 0 ? string.Empty : line.Substring (index + marker.Length) ;

Answer 2

If you're using 3.5 this is trivial with Linq:

public static string GetTextAfterMarker2(string line, string marker)
{
  string result = line.Split(new string[] { marker }, StringSplitOptions.None).Last();
  return line.Equals(result) ? string.Empty : result;
}

Answer 3

I'd do it this way

    public static string GetTextAfterMarker(string line, string marker)
    {
        int pos = line.LastIndexOf(marker);
        if (pos < 0)
            return string.Empty;
        else
            return line.Substring(pos + marker.Length);
    }

No need to call split, no need to create an array of items, which basically you're just going to throw away.

Much faster and less resource heavy.

Answer 4

If I'm reading your code correctly, you're trying to get the last instance?

string[] splits = line.Split(new string[] { marker }, StringSplitOptions.None);
return (splits.Length == 1) ? string.Empty : splits[splits.Length-1];

Answer 5

Altough I don't know wether you asked this out of simple curiosity, I would recommend you to not being afraid of creating auxiliary variables if that makes your code more readable. You will rarely degrade your code performance for using these extra variables.

Answer 6

public static string GetTextAfterMarker(string line, string marker)
{
    string result = line.Split(new string[] { marker }, StringSplitOptions.None)[line.Split(new string[] { marker }, StringSplitOptions.None).Count()-1];
    return line.Equals(result) ? string.Empty : result;
}

Why you'd want to do that though is beyond me... It's messy, to say the least.

Perhaps:

public static string GetTextAfterMarker(string line, string marker)
{
    string[] tmp = line.Split(new string[] { marker }, StringSplitOptions.None);
    string result = tmp[tmp.Length-1];
    return line.Equals(result) ? string.Empty : result;
}

Or you might even consider using .IndexOf and .Substring instead, something like this (untested):

public static string GetTextAfterMarker(string line, string marker)
{
    int index = line.LastIndexOf(marker);
    return index < 0 ? string.Empty : line.Substring(index + marker.Length);
}

Answer 7

What about:

public static string GetTextAfterMarker(string line, string marker)
{
    var items = line.Split(new[] {marker}, StringSplitOptions.None);

    string result = items[items.Length-1];
    return line.Equals(result) ? string.Empty : result;
}

Answer 8

You could always use regular expressions instead of split:

    public static string GetTextAfterMarker(string line, string marker)
    {
        if (String.IsNullOrEmpty(line))
            throw new ArgumentException("line is null or empty.", "line");
        if (String.IsNullOrEmpty(marker))
            throw new ArgumentException("marker is null or empty.", "marker");
        string EscapedMarker = Regex.Escape(marker);
        return Regex.Match(line, EscapedMarker + "([^" + EscapedMarker + "]+)").Groups[1].Value;
    }