how can I take 3 string arrays(contains files) into a single array

Question

string[] filesHD = Directory.GetFiles(dirPath, filepattern1);

string[] filesDT = Directory.GetFiles(dirPath, filepattern2);

string[] filesTD = Directory.GetFiles(dirPath, filepattern3);

My filesHD[] array contains 2 files. filesDT[] contains 2 files and filesTD[] also contains 2 files.

I want to create a single string Array which will contain all the 6 files of filesHD, filesDT, filesTD.

string[] Allfiles = new string [filesHD + filesDT + filesTD]

http://stackoverflow.com/questions/1547252/how-do-i-concatenate-two-arrays-in-c — BryanJ, Jan 16 '14 at 17:26

Pete Garafano · Answer 1 · 2014-01-16T17:37:34.133

5

There are several methods to do this, in C# the easiest is probably:

var allFiles = filesHD.Union(filesDT).Union(filesTD);

OR

var allFiles = filesHD.Concat(filesDT).Concat(filesTD);

You can end it with a call to .ToArray() if you will be enumerating it more than once, if you are just going to foreach over it once, don't worry about the .ToArray(). The difference between Union and Concat is Union uses the default equality comparer to ignore duplicates.

edited Jan 16 '14 at 17:37

answered Jan 16 '14 at 17:31

Pete Garafano

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`Concat` is better as `Union` will strip out duplicates, we don't want that. – unlimit Jan 16 '14 at 17:36
@unlimit yeah, I noted that at the end of my answer. However, it may be something the user wants. – Pete Garafano Jan 16 '14 at 17:37
@unlimit but if we're talking about files from the same folder, we might want to strip out duplicates... – nurchi Jan 16 '14 at 17:45
@nurchi from the question it does not look like OP wants that. However, this answers explains both the options. – unlimit Jan 16 '14 at 17:50

Max · Answer 2 · 2014-01-16T17:36:53.993

1

Could you try following code?

List<string> AllFiles = new List<string>();
AllFiles.Concat(filesHD);
AllFiles.Concat(filesDT);
AllFiles.Concat(filesTD);

var strAllFiles = AllFiles.ToArray();

Add reference: Using System.Linq;

Note: Typed without compiler, couldn't check for syntax errors.

edited Jan 16 '14 at 17:36

answered Jan 16 '14 at 17:30

Max

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FYI to your note: The `ToList` on each array isn't necessary. `Concat` takes `IEnumerable`. – Pete Garafano Jan 16 '14 at 17:35

score 1 · Answer 3 · answered Jan 16 '14 at 17:38

If you want to be simple, you could also try the following:

List<string> lstAllFiles=new List<string>();
lstAllFiles.AddRange(filesHD);
lstAllFiles.AddRange(filesDT);
lstAllFiles.AddRange(filesTD);
string[] strAllFiles=lstAllFiles.ToArray();

This method does not use Linq...
Hope this helps.

how can I take 3 string arrays(contains files) into a single array

3 Answers3