拆分文件名

Question

I've a filename:

NewReport-20140423_17255375-BSIQ-2wd28830-841c-4d30-95fd-a57a7aege412.zip

How can i split the above filename to 4 string groups.

NewReport
20140423_17255375
BSIQ
2wd28830-841c-4d30-95fd-a57a7aege412.zip

I tried:

 string[] strFileTokens = filename.Split(new char[]{'-'} , StringSplitOptions.None);

but i'm not getting the above required four strings

Answer 1

You can specify the maximum number of substrings to return:

var strFileTokens = filename.Split(new[] { '-' }, 4, StringSplitOptions.None);

This will avoid splitting 2wd28830-841c-4d30-95fd-a57a7aege412.zip into additional "pieces".

(Also, you can drop StringSplitOptions.None since that's the default.)

---

Internally, it creates an array of substrings inside a loop, and it only loops the number of times you specify (or the maximum number of delimiters available in your string, whichever is less).

for (int i = 0; i < numActualReplaces && currIndex < Length; i++)
{
    splitStrings[arrIndex++] = Substring(currIndex, sepList[i] - currIndex );
    currIndex = sepList[i] + ((lengthList == null) ? 1 : lengthList[i]); 
}

The variable numActualReplaces is the minimum of either the count you specify, or the number of actual delimiters present in your string. (That way, if you specify a larger number like 30, but you only have 7 hyphens in the string, you won't get an exception. Actually, when you don't specify a number at all, it's actually using Int32.MaxValue without you even realizing it.)

---

You updated your question to say you're using Silverlight, which doesn't have he overloads with Count . That's really annoying, because under the hood the string class still supports it. They just didn't provide a way to pass in your own value. It uses a hard-coded int.MaxValue .

You could create your own method to bring back the desired functionality. I haven't tested this extension method out for all edge-cases, but it does work with your string.

public static class StringSplitExtension
{
    public static string[] SplitByCount(this string input, char[] separator, int count)
    {
        if (count < 0)
            throw new ArgumentOutOfRangeException("count");

        if (count == 0)
            return new string[0];

        var numberOfSeparators = input.Count(separator.Contains);

        var numActualReplaces = Math.Min(count, numberOfSeparators + 1);

        var splitString = new string[numActualReplaces];

        var index = -1;
        for (var i = 1; i <= numActualReplaces; i++)
        {
            var nextIndex = input.IndexOfAny(separator, index + 1);
            if (nextIndex == -1 || i == numActualReplaces)
                splitString[i - 1] = input.Substring(index + 1);
            else
                splitString[i - 1] = input.Substring(index + 1, nextIndex - index - 1);
            index = nextIndex;
        }

        return splitString;
    }
}

Make sure it's somewhere accessible to your UserControl, then call it like this:

var strFileTokens = filename.SplitByCount(new[] { '-' }, 4)

Answer 2

如果你调用带有count参数的Split的重载，它可以工作：

var myArray = filename.Split(new char[] { '-' }, 4);

Answer 3

Since you're using silverlight as shown in your follow up question which doesn't have this overload i show a different approach. You could use LINQ's Skip , Take + string.Join to get one string :

Your sample string:

string filename = "NewReport-20140423_17255375-BSIQ-2wd28830-841c-4d30-95fd-a57a7aege412.zip";

An array with all parts:

string[] allTokens = filename.Split(new[] { '-' }, StringSplitOptions.RemoveEmptyEntries);

var firstThreeToken = allTokens.Take(3);  // first three
var lastTokens = allTokens.Skip(3);       // the last part 
string lastToken = string.Join("-", lastTokens); // last tokens as single string
string[] allToken = firstThreeToken.Concat(new[] { lastToken }).ToArray();

Result:

"NewReport" 
"20140423_17255375"
"BSIQ"
"2wd28830-841c-4d30-95fd-a57a7aege412.zip"  

Answer 4

You can use the Regex.Split method which offers an overload that takes the count param.

Regex reg = new Regex( "-" );
string filename = "NewReport-20140423_17255375-BSIQ-2wd28830-841c-4d30-95fd-a57a7aege412.zip";
var parts = reg.Split( filename, 4 );

Answer 5

Obviously you are getting more parts because the last part of your file also contains "-".

An easy way to solve it is to join the remaining parts like this:

String lastpart = string.Join("-", names, 3, names.Length - 3);