VB.Net Tutorial/Data Type/String Compare — различия между версиями

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Текущая версия на 15:54, 26 мая 2010

Compare String value in If statement

<source lang="vbnet">Module Module1

   Sub Main()
       Dim Language As String = "English"
       If (Language = "English") Then
           Console.WriteLine("Hello, world!")
       ElseIf (Language = "Spanish") Then
           Console.WriteLine("Hola, mundo")
       End If
   End Sub

End Module</source>

Hello, world!

Comparing strings: Equals, =, String.Equals() and CompareTo

<source lang="vbnet">Module Tester

  Sub Main()
     Dim string1 As String = "hello"
     Dim string2 As String = "good bye"
     Dim string3 As String = "Happy Birthday"
     Dim string4 As String = "happy birthday"
     Dim output As String
     Dim quotes As Char = ChrW(34)
     If (string1.Equals("hello")) Then
        Console.WriteLine("string1 equals hello")
     Else
        Console.WriteLine("not equal ")
     End If
     " test for equality with =
     If string1 = "hello" Then
        Console.WriteLine("string1 equals " & quotes & "hello" & quotes )
     Else
        Console.WriteLine("string1 does not equal " & quotes & "hello" & quotes)
     End If
     If (String.Equals(string3, string4)) Then
        Console.WriteLine("string3 equals string4")
     Else
        Console.WriteLine("string3 does not equal string4")
     End If
     " test CompareTo
     Console.WriteLine("string1.rupareTo(string2) is " & _
        string1.rupareTo(string2) & vbCrLf & _
        "string2.rupareTo(string1) is " & _
        string2.rupareTo(string1) & vbCrLf & _
        "string1.rupareTo(string1) is " & _
        string1.rupareTo(string1) & vbCrLf & _
        "string3.rupareTo(string4) is " & _
        string3.rupareTo(string4) & vbCrLf & _
        "string4.rupareTo(string3) is " & _
        string4.rupareTo(string3))
  End Sub " Main

End Module</source>

string1 equals hello
string1 equals "hello
string3 does not equal string4
string1.rupareTo(string2) is 1
string2.rupareTo(string1) is -1
string1.rupareTo(string1) is 0
string3.rupareTo(string4) is 1
string4.rupareTo(string3) is -1

String Compare with case sensitive and insensitive

<source lang="vbnet">Class Tester

    Shared Sub Main( )
        Dim s1 As [String] = "abcd"
        Dim s2 As [String] = "ABCD"
        Dim result As Integer 
        result = [String].rupare(s1, s2)
        Console.WriteLine("compare s1: {0}, s2: {1}, result: {2}" _
          & Environment.NewLine, s1, s2, result)
        result = [String].rupare(s1, s2, True)
        Console.WriteLine("Compare insensitive. result: {0}" _
           & Environment.NewLine, result)
    End Sub
End Class</source>
compare s1: abcd, s2: ABCD, result: -1
Compare insensitive. result: 0

String Equals with overloaded operator, member method and static member method

<source lang="vbnet">Option Strict On

Imports System
Class Tester
    Public Shared Sub Main( )
        Dim s1 As String = "abcd"
        Dim s2 As String = "ABCD"
        " the String copy method
        Dim s5 As String = String.Copy(s2)
        Console.WriteLine("s5 copied from s2: {0}", s5)
        " copy with the overloaded operator
        Dim s6 As String = s5
        Console.WriteLine("s6 = s5: {0}", s6)
        " member method
        Console.WriteLine("Does s6.Equals(s5)?: {0}", s6.Equals(s5))
        " shared method
        Console.WriteLine("Does Equals(s6,s5)?: {0}", _
           String.Equals(s6, s5))
    End Sub "Main
End Class "Tester</source>
s5 copied from s2: ABCD
s6 = s5: ABCD
Does s6.Equals(s5)?: True
Does Equals(s6,s5)?: True