Cara: Menghitung Kemunculan Kata dalam String (LINQ) (Visual Basic)

Contoh ini memperlihatkan cara menggunakan kueri LINQ untuk menghitung kemunculan kata tertentu dalam string. Perhatikan bahwa untuk melakukan hitungan, pertama-tama metode Split dipanggil untuk membuat array kata. Ada biaya performa untuk metode Split. Jika satu-satunya operasi pada string adalah menghitung kata-kata, Anda harus mempertimbangkan untuk menggunakan Matches atau IndexOf sebagai gantinya. Namun, jika performa bukan masalah penting, atau Anda telah membagi kalimat untuk melakukan jenis kueri lain di atasnya, maka masuk akal untuk menggunakan LINQ untuk menghitung kata atau frasa juga.

Contoh

Class CountWords

    Shared Sub Main()

        Dim text As String = "Historically, the world of data and the world of objects" &
                  " have not been well integrated. Programmers work in C# or Visual Basic" &
                  " and also in SQL or XQuery. On the one side are concepts such as classes," &
                  " objects, fields, inheritance, and .NET Framework APIs. On the other side" &
                  " are tables, columns, rows, nodes, and separate languages for dealing with" &
                  " them. Data types often require translation between the two worlds; there are" &
                  " different standard functions. Because the object world has no notion of query, a" &
                  " query can only be represented as a string without compile-time type checking or" &
                  " IntelliSense support in the IDE. Transferring data from SQL tables or XML trees to" &
                  " objects in memory is often tedious and error-prone."

        Dim searchTerm As String = "data"

        ' Convert the string into an array of words.
        Dim dataSource As String() = text.Split(New Char() {" ", ",", ".", ";", ":"},
                                                 StringSplitOptions.RemoveEmptyEntries)

        ' Create and execute the query. It executes immediately
        ' because a singleton value is produced.
        ' Use ToLower to match "data" and "Data"
        Dim matchQuery = From word In dataSource
                      Where word.ToLowerInvariant() = searchTerm.ToLowerInvariant()
                      Select word

        ' Count the matches.
        Dim count As Integer = matchQuery.Count()
        Console.WriteLine(count & " occurrence(s) of the search term """ &
                          searchTerm & """ were found.")

        ' Keep console window open in debug mode.
        Console.WriteLine("Press any key to exit.")
        Console.ReadKey()
    End Sub
End Class
' Output:
' 3 occurrence(s) of the search term "data" were found.

Mengkompilasi kode

Buat proyek aplikasi konsol Visual Basic, dengan pernyataan Imports untuk namespace System.Linq.

Lihat juga

• LINQ dan String (Visual Basic)