CSharp (C #) - How to Sort Files Returned by DirectoryInfo.GetFiles Using Natural Sort

Views: 1.076 views

Reading Time: 4 minutes

Hello people,
Good Morning!

In this post I will take a very simple approach to something that many .NET developers are looking for on the internet, as I sought this solution myself, but which is a little tricky to find because most of the posted solutions do not work.

My problem was that I use a C # function a lot in my CLR to list files from a directory (I had already posted this function in the post SQL Server - How to list, read, write, copy, delete and move files with CLR (C #)), but the fact that the files are not sorted correctly always bothered me, and I decided to improve it.

Example of current usage:

Even if you use an ORDER BY clause to try to sort, it won't work, because SQL Server will do string sorting using alphanumeric sorting.

How the alphanumeric string sorting algorithm works
This type of algorithm uses ASCII code to sort data by comparing character by character until the string ends or the ASCII code of one string is shorter than the other. Thus, in a comparison between 100 File and 20 File, the comparison will be made as follows:

Each character of the word "File" will be compared between the 2 strings. As they are the same, the algorithm will proceed to the rest of the string
The character "1" will be compared with the character "2". As it is smaller, the sorting ends there, placing “File 100” before “File 20”

How the Natural Sort String Sorting Algorithm Works
Just as I am uncomfortable with this ordering, which is the standard for the vast majority of programming languages, many people also dislike the “100” before “2000” and to give a more “humanized” view, the Natural Sort algorithm was created, which separates numerical characters from letters, and sorts them separately. The numbers are compared numerically (where 100 is greater than 20), and the strings he continues using the ASCII code.

To implement the Natural Sort algorithm, I found code in the James McCormack blog to create an ICompare class in C # and thus sort my files in my function (and any other list of files you need to sort).

View Source Code for ICompare Class

public class NaturalSortComparer<T> : IComparer<string>, IDisposable
{
    private readonly bool _isAscending;

    public NaturalSortComparer(bool inAscendingOrder = true)
    {
        this._isAscending = inAscendingOrder;
    }

    public int Compare(string x, string y)
    {
        throw new NotImplementedException();
    }

    int IComparer<string>.Compare(string x, string y)
    {
        if (x == y)
            return 0;

        string[] x1, y1;

        if (!table.TryGetValue(x, out x1))
        {
            x1 = Regex.Split(x.Replace(" ", ""), "([0-9]+)");
            table.Add(x, x1);
        }

        if (!table.TryGetValue(y, out y1))
        {
            y1 = Regex.Split(y.Replace(" ", ""), "([0-9]+)");
            table.Add(y, y1);
        }

        int returnVal;

        for (var i = 0; i < x1.Length && i < y1.Length; i++)
        {

            if (x1[i] == y1[i]) continue;

            returnVal = PartCompare(x1[i], y1[i]);
            return _isAscending ? returnVal : -returnVal;
        }

        if (y1.Length > x1.Length)
        {
            returnVal = 1;
        }
        else if (x1.Length > y1.Length)
        {
            returnVal = -1;
        }
        else
        {
            returnVal = 0;
        }

        return _isAscending ? returnVal : -returnVal;
    }

    private static int PartCompare(string left, string right)
    {
        int x, y;
        if (!int.TryParse(left, out x))
            return string.Compare(left, right, StringComparison.InvariantCulture);

        return !int.TryParse(right, out y) ? string.Compare(left, right, StringComparison.InvariantCulture) : x.CompareTo(y);
    }

    private Dictionary<string, string[]> table = new Dictionary<string, string[]>();

    public void Dispose()
    {
        table.Clear();
        table = null;
    }
}

public class NaturalSortComparer<T> : IComparer<string>, IDisposable

{

private readonly bool _isAscending;

public NaturalSortComparer(bool inAscendingOrder = true)

{

this._isAscending = inAscendingOrder;

}

public int Compare(string x, string y)

{

throw new NotImplementedException();

}

int IComparer<string>.Compare(string x, string y)

{

if (x == y)

return 0;

string[] x1, y1;

if (!table.TryGetValue(x, out x1))

{

x1 = Regex.Split(x.Replace(" ", ""), "([0-9]+)");

table.Add(x, x1);

}

if (!table.TryGetValue(y, out y1))

{

y1 = Regex.Split(y.Replace(" ", ""), "([0-9]+)");

table.Add(y, y1);

}

int returnVal;

for (var i = 0; i < x1.Length && i < y1.Length; i++)

{

if (x1[i] == y1[i]) continue;

returnVal = PartCompare(x1[i], y1[i]);

return _isAscending ? returnVal : -returnVal;

}

if (y1.Length > x1.Length)

{

returnVal = 1;

}

else if (x1.Length > y1.Length)

{

returnVal = -1;

}

else

{

returnVal = 0;

}

return _isAscending ? returnVal : -returnVal;

}

private static int PartCompare(string left, string right)

{

int x, y;

if (!int.TryParse(left, out x))

return string.Compare(left, right, StringComparison.InvariantCulture);

return !int.TryParse(right, out y) ? string.Compare(left, right, StringComparison.InvariantCulture) : x.CompareTo(y);

}

private Dictionary<string, string[]> table = new Dictionary<string, string[]>();

public void Dispose()

{

table.Clear();

table = null;

}

Now I need to change my file listing function (I also include a boolean flag to list files within subdirectories or not) and include an OrderBy function through the LINQ library.

In this excerpt:

foreach (var fileInfo in directories)

1	foreach (var fileInfo in directories)

I changed to this snippet:

foreach (var fileInfo in directories.OrderBy(fileInfo => fileInfo.Name, new NaturalSortComparer<string>()))

1	foreach (var fileInfo in directories.OrderBy(fileInfo => fileInfo.Name, new NaturalSortComparer<string>()))

And with that, our problem was solved, where we have the following result:

View Full Source Code for this Function

using System.IO;
using System.Collections;
using System.Data.SqlTypes;
using System.Linq;

public partial class UserDefinedFunctions
{

    private class FileProperties
    {

        public SqlInt32 NrLinha;
        public SqlString Tipo;
        public SqlString FileName;
        public SqlString FileNameWithoutExtension;
        public SqlString DirectoryName;
        public SqlString Extension;
        public SqlString FullName;
        public SqlInt64 FileSize;
        public SqlBoolean IsReadOnly;
        public SqlDateTime CreationTime;
        public SqlDateTime LastAccessTime;
        public SqlDateTime LastWriteTime;


        public FileProperties(SqlInt32 nrLinha, SqlString tipo, SqlString fileName, SqlString fileNameWithoutExtension, SqlString directoryName, SqlString extension, SqlString fullName, SqlInt64 fileSize, SqlBoolean isReadOnly, SqlDateTime creationTime, SqlDateTime lastAccessTime, SqlDateTime lastWriteTime)
        {

            NrLinha = nrLinha;
            Tipo = tipo;
            FileNameWithoutExtension = fileNameWithoutExtension;
            FileName = fileName;
            DirectoryName = directoryName;
            Extension = extension;
            FullName = fullName;
            FileSize = fileSize;
            IsReadOnly = isReadOnly;
            CreationTime = creationTime;
            LastAccessTime = lastAccessTime;
            LastWriteTime = lastWriteTime;

        }
    }

    [Microsoft.SqlServer.Server.SqlFunction(
        FillRowMethodName = "listarArquivos",
        TableDefinition = "Nr_Linha int, Fl_Tipo nvarchar(50), Nm_Arquivo nvarchar(500), Nm_Arquivo_Sem_Extensao nvarchar(500), Nm_Diretorio nvarchar(500), " +
                          "Nm_Extensao nvarchar(20), Nm_Completo nvarchar(500), Qt_Tamanho bigint, Fl_Somente_Leitura bit, Dt_Criacao datetime, " +
                          "Dt_Ultimo_Acesso datetime, Dt_Modificacao datetime"
    )]
    public static IEnumerable fncArquivo_Listar(string Ds_Diretorio, string Ds_Filtro, bool Fl_Recursivo)
    {

        var recursivo = (Fl_Recursivo) ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly;

        var filePropertiesCollection = new ArrayList();
        var dirInfo = new DirectoryInfo(Ds_Diretorio);
        var files = dirInfo.GetFiles(Ds_Filtro, recursivo);
        var directories = dirInfo.GetDirectories(Ds_Filtro);
        var contador = 1;

        foreach (var fileInfo in directories.OrderBy(fileInfo => fileInfo.Name, new NaturalSortComparer<string>()))
        {

            filePropertiesCollection.Add(new FileProperties(
                contador,
                "Diretorio",
                fileInfo.Name,
                fileInfo.Name,
                fileInfo.Name,
                "",
                fileInfo.FullName + "\\",
                0,
                false,
                fileInfo.CreationTime,
                fileInfo.LastAccessTime,
                fileInfo.LastWriteTime
            ));

            contador++;

        }



        foreach (var fileInfo in files.OrderBy(fileInfo => fileInfo.DirectoryName, new NaturalSortComparer<string>()).ThenBy(fileInfo => fileInfo.Name, new NaturalSortComparer<string>()))
        {

            filePropertiesCollection.Add(new FileProperties(
                contador,
                "Arquivo",
                fileInfo.Name,
                (fileInfo.Extension.Length > 0) ? fileInfo.Name.Replace(fileInfo.Extension, "") : "",
                fileInfo.DirectoryName,
                fileInfo.Extension.ToLower(),
                fileInfo.FullName,
                fileInfo.Length,
                fileInfo.IsReadOnly,
                fileInfo.CreationTime,
                fileInfo.LastAccessTime,
                fileInfo.LastWriteTime
            ));

            contador++;

        }

        return filePropertiesCollection;

    }

    protected static void listarArquivos(object objFileProperties, out SqlInt32 nrLinha, out SqlString tipo, out SqlString fileName, out SqlString fileNameWithoutExtension, out SqlString directoryName, out SqlString extension, out SqlString fullName, out SqlInt64 fileSize, out SqlBoolean isReadOnly, out SqlDateTime creationTime, out SqlDateTime lastAccessTime, out SqlDateTime lastWriteTime)
    {

        var fileProperties = (FileProperties) objFileProperties;

        nrLinha = fileProperties.NrLinha;
        tipo = fileProperties.Tipo;
        fileName = fileProperties.FileName;
        fileNameWithoutExtension = fileProperties.FileNameWithoutExtension;
        directoryName = fileProperties.DirectoryName;
        extension = fileProperties.Extension;
        fullName = fileProperties.FullName;
        fileSize = fileProperties.FileSize;
        isReadOnly = fileProperties.IsReadOnly;
        creationTime = fileProperties.CreationTime;
        lastAccessTime = fileProperties.LastAccessTime;
        lastWriteTime = fileProperties.LastWriteTime;

    }

}

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

using System.IO;

using System.Collections;

using System.Data.SqlTypes;

using System.Linq;

public partial class UserDefinedFunctions

{

private class FileProperties

{

public SqlInt32 NrLinha;

public SqlString Tipo;

public SqlString FileName;

public SqlString FileNameWithoutExtension;

public SqlString DirectoryName;

public SqlString Extension;

public SqlString FullName;

public SqlInt64 FileSize;

public SqlBoolean IsReadOnly;

public SqlDateTime CreationTime;

public SqlDateTime LastAccessTime;

public SqlDateTime LastWriteTime;

public FileProperties(SqlInt32 nrLinha, SqlString tipo, SqlString fileName, SqlString fileNameWithoutExtension, SqlString directoryName, SqlString extension, SqlString fullName, SqlInt64 fileSize, SqlBoolean isReadOnly, SqlDateTime creationTime, SqlDateTime lastAccessTime, SqlDateTime lastWriteTime)

{

NrLinha = nrLinha;

Tipo = tipo;

FileNameWithoutExtension = fileNameWithoutExtension;

FileName = fileName;

DirectoryName = directoryName;

Extension = extension;

FullName = fullName;

FileSize = fileSize;

IsReadOnly = isReadOnly;

CreationTime = creationTime;

LastAccessTime = lastAccessTime;

LastWriteTime = lastWriteTime;

}

[Microsoft.SqlServer.Server.SqlFunction(

FillRowMethodName = "listarArquivos",

TableDefinition = "Nr_Linha int, Fl_Tipo nvarchar(50), Nm_Arquivo nvarchar(500), Nm_Arquivo_Sem_Extensao nvarchar(500), Nm_Diretorio nvarchar(500), " +

"Nm_Extensao nvarchar(20), Nm_Completo nvarchar(500), Qt_Tamanho bigint, Fl_Somente_Leitura bit, Dt_Criacao datetime, " +

"Dt_Ultimo_Acesso datetime, Dt_Modificacao datetime"

)]

public static IEnumerable fncArquivo_Listar(string Ds_Diretorio, string Ds_Filtro, bool Fl_Recursivo)

{

var recursivo = (Fl_Recursivo) ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly;

var filePropertiesCollection = new ArrayList();

var dirInfo = new DirectoryInfo(Ds_Diretorio);

var files = dirInfo.GetFiles(Ds_Filtro, recursivo);

var directories = dirInfo.GetDirectories(Ds_Filtro);

var contador = 1;

foreach (var fileInfo in directories.OrderBy(fileInfo => fileInfo.Name, new NaturalSortComparer<string>()))

{

filePropertiesCollection.Add(new FileProperties(

contador,

"Diretorio",

fileInfo.Name,

"",

fileInfo.FullName + "\\",

false,

fileInfo.CreationTime,

fileInfo.LastAccessTime,

fileInfo.LastWriteTime

));

contador++;

}

foreach (var fileInfo in files.OrderBy(fileInfo => fileInfo.DirectoryName, new NaturalSortComparer<string>()).ThenBy(fileInfo => fileInfo.Name, new NaturalSortComparer<string>()))

{

filePropertiesCollection.Add(new FileProperties(

contador,

"Arquivo",

fileInfo.Name,

(fileInfo.Extension.Length > 0) ? fileInfo.Name.Replace(fileInfo.Extension, "") : "",

fileInfo.DirectoryName,

fileInfo.Extension.ToLower(),

fileInfo.FullName,

fileInfo.Length,

fileInfo.IsReadOnly,

fileInfo.CreationTime,

fileInfo.LastAccessTime,

fileInfo.LastWriteTime

));

contador++;

}

return filePropertiesCollection;

}

protected static void listarArquivos(object objFileProperties, out SqlInt32 nrLinha, out SqlString tipo, out SqlString fileName, out SqlString fileNameWithoutExtension, out SqlString directoryName, out SqlString extension, out SqlString fullName, out SqlInt64 fileSize, out SqlBoolean isReadOnly, out SqlDateTime creationTime, out SqlDateTime lastAccessTime, out SqlDateTime lastWriteTime)

{

var fileProperties = (FileProperties) objFileProperties;

nrLinha = fileProperties.NrLinha;

tipo = fileProperties.Tipo;

fileName = fileProperties.FileName;

fileNameWithoutExtension = fileProperties.FileNameWithoutExtension;

directoryName = fileProperties.DirectoryName;

extension = fileProperties.Extension;

fullName = fileProperties.FullName;

fileSize = fileProperties.FileSize;

isReadOnly = fileProperties.IsReadOnly;

creationTime = fileProperties.CreationTime;

lastAccessTime = fileProperties.LastAccessTime;

lastWriteTime = fileProperties.LastWriteTime;

}

Thank you so much for visiting and see you next post!

Other Languages

Subscribe to a blog by email

Blog Views

Categories

Azure Banking Admin Course

SQL Server Security Course

My Certifications

Posts Archive

Recent Posts

Other Languages

Are you looking for something?

Subscribe to Blog by Email

Total Views

Courses and training

Microsoft MVP

Acknowledgments and Certificates

Categories

Archives

Recent Posts

CSharp (C #) - How to sort files returned by DirectoryInfo.GetFiles using Natural Sort

You may also like ...

Leave a Comment Cancel reply

You may also like ...

Using the Pushbullet API to send SMS messages in C #, PHP, Java, or SQL Server (with CLR)

SQL Server - Table-valued function to break a string into lines up to N characters long

SQL Server - How to use regular expressions (RegExp) in your database

Leave a Comment Cancel reply