VB.Net Tutorial/Data Type/String Find
Содержание
- 1 Demonstrating StartsWith and EndsWith methods
- 2 Return the index of the string
- 3 String Index of any
- 4 Use IndexOfAny to find first occurrence of character in array
- 5 Use IndexOf to locate a substring in a string
- 6 Use LastIndexOfAny to find first occurrence of character in array
- 7 Use LastIndexOf to find a substring in a string
Demonstrating StartsWith and EndsWith methods
<source lang="vbnet">Module Tester
Sub Main() Dim strings As String() Dim output As String = "" Dim i As Integer Dim quotes As Char = ChrW(34) strings = New String() {"started", "starting", _ "ended", "ending"} For i = 0 To strings.GetUpperBound(0) If strings(i).StartsWith("st") Then Console.WriteLine(" starts with st") End If Next For i = 0 To strings.GetUpperBound(0) If strings(i).EndsWith("ed") Then Console.WriteLine(" ends with ed" ) End If Next End Sub " Main
End Module</source>
starts with st starts with st ends with ed ends with ed
Return the index of the string
<source lang="vbnet">Option Strict On
Imports System Class Tester Public Shared Sub Main( ) Dim s1 As String = "abcd" Dim s2 As String = "ABCD" Dim s3 As String = "AAAAs " s3 = s3 & "development" Console.WriteLine("s3: {0}", s3) Console.Write("The first occurrence of a ") Console.WriteLine(s3.IndexOf("a"))
End Sub "Main End Class "Tester</source>
s3: AAAAs development The first occurrence of a -1
String Index of any
<source lang="vbnet">public class Test
public Shared Sub Main Dim s1 As New String("Greeting") Console.WriteLine(s1.IndexOfAny("tin")) End Sub
End class</source>
4
Use IndexOfAny to find first occurrence of character in array
<source lang="vbnet">Module Tester
Sub Main() Dim letters As String = "abcdefghijklmabcdefghijklm" Dim searchLetters As Char() = New Char() {"c"c, "a"c, "$"c} Console.WriteLine("First occurrence of ""c""," & _ " ""a"" or ""$"" is located at " & _ letters.IndexOfAny(searchLetters)) Console.WriteLine("First occurrence of ""c"", ""a"" or " & _ """$"" is located at " & _ letters.IndexOfAny(searchLetters, 7)) Console.WriteLine("First occurrence of ""c"", ""a"" or " & _ """$"" is located at " & _ letters.IndexOfAny(searchLetters, 20, 5)) End Sub
End Module</source>
First occurrence of "c", "a" or "$" is located at 0 First occurrence of "c", "a" or "$" is located at 13 First occurrence of "c", "a" or "$" is located at -1
Use IndexOf to locate a substring in a string
<source lang="vbnet">Module Tester
Sub Main() Dim letters As String = "abcdefghijklmabcdefghijklm" Dim searchLetters As Char() = New Char() {"c"c, "a"c, "$"c} Console.WriteLine(letters.IndexOf("def")) Console.WriteLine(letters.IndexOf("def", 7)) Console.WriteLine(letters.IndexOf("hello", 5, 15)) End Sub
End Module</source>
3 16 -1
Use LastIndexOfAny to find first occurrence of character in array
<source lang="vbnet">Module Tester
Sub Main() Dim letters As String = "abcdefghijklmabcdefghijklm" Dim searchLetters As Char() = New Char() {"c"c, "a"c, "$"c} Console.WriteLine("Last occurrence of ""c""," & _ " ""a"" or ""$"" is located at " & _ letters.LastIndexOfAny(searchLetters)) Console.WriteLine("Last occurrence of ""c"", ""a"" or " & _ """$"" is located at " & _ letters.LastIndexOfAny(searchLetters, 1)) Console.WriteLine("Last occurrence of ""c"", ""a"" or " & _ """$"" is located at " & _ letters.LastIndexOfAny(searchLetters, 25, 5)) End Sub
End Module</source>
Last occurrence of "c", "a" or "$" is located at 15 Last occurrence of "c", "a" or "$" is located at 0 Last occurrence of "c", "a" or "$" is located at -1
Use LastIndexOf to find a substring in a string
<source lang="vbnet">Module Tester
Sub Main() Dim letters As String = "abcdefghijklmabcdefghijklm" Dim searchLetters As Char() = New Char() {"c"c, "a"c, "$"c} Console.WriteLine(letters.LastIndexOf("def")) Console.WriteLine(letters.LastIndexOf("def", 25)) Console.WriteLine(letters.LastIndexOf("hello", 20, 15)) End Sub
End Module</source>
16 16 -1