How can I search an array in VB NET

Question

I want to be able to effectively search an array for the contents of a string  Example     dim arr   as string   ravi   Kumar   Ravi   Ramesh     I pass the value is  ra  and I want it to return the index of 2 and 3   How can I do this in VB NET

User · Answer

VB  Dim arr   As String     ravi    Kumar    Ravi    Ramesh   Dim result   arr Where Function a  a Contains  ra    Select Function s  Array IndexOf arr  s   ToArray     C   string   arr      ravi    Kumar    Ravi    Ramesh     var result   arr Where a   gt  a Contains  Ra    Select a   gt  Array IndexOf arr  a   ToArray      -----Detailed------  Module Module1      Sub Main           Dim arr   As String     ravi    Kumar    Ravi    Ramesh           Dim searchStr    ra           Not case sensitive - checks if item starts with searchStr         Dim result1   arr Where Function a  a ToLower StartsWith searchStr   Select Function s  Array IndexOf arr  s   ToArray          Case sensitive - checks if item starts with searchStr         Dim result2   arr Where Function a  a StartsWith searchStr   Select Function s  Array IndexOf arr  s   ToArray          Not case sensitive - checks if item contains searchStr         Dim result3   arr Where Function a  a ToLower Contains searchStr   Select Function s  Array IndexOf arr  s   ToArray         Stop     End Sub  End Module

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Dim inputString As String    ra  Enumerable Range 0  arr Length  Where Function x  arr x  ToLower   Contains inputString ToLower

User · Answer

It s not exactly clear how you want to search the array  Here are some alternatives   Find all items containing the exact string  Ra   returns items 2 and 3    Dim result As String     Array FindAll arr  Function s  s Contains  Ra      Find all items starting with the exact string  Ra   returns items 2 and 3    Dim result As String     Array FindAll arr  Function s  s StartsWith  Ra      Find all items containing any case version of  ra   returns items 0  2 and 3    Dim result As String     Array FindAll arr  Function s  s ToLower   Contains  ra      Find all items starting with any case version of  ra   retuns items 0  2 and 3    Dim result As String     Array FindAll arr  Function s  s ToLower   StartsWith  ra      -  If you are not using VB 9  then you don t have anonymous functions  so you have to create a named function   Example   Function ContainsRa s As String  As Boolean    Return s Contains  Ra   End Function   Usage   Dim result As String     Array FindAll arr  ContainsRa    Having a function that only can compare to a specific string isn t always very useful  so to be able to specify a string to compare to you would have to put it in a class to have somewhere to store the string   Public Class ArrayComparer     Private  compareTo As String     Public Sub New compareTo As String         compareTo   compareTo    End Sub     Function Contains s As String  As Boolean       Return s Contains  compareTo     End Function     Function StartsWith s As String  As Boolean       Return s StartsWith  compareTo     End Function  End Class   Usage   Dim result As String     Array FindAll arr  New ArrayComparer  Ra   Contains

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check this            string   strArray      ABC    BCD    CDE    DEF    EFG    FGH    GHI             Array IndexOf strArray   C       not found  returns -1         Array IndexOf strArray   CDE       found  returns index

User · Answer

This would do the trick  returning the values at indeces 0  2 and 3   Array FindAll arr  Function s  s ToLower   StartsWith  ra

User · Answer

compare properties in the array if one matches the input then set something to the value of the loops current position  which is also the index of the current looked up item   simple eg   dim x y z as integer dim aNames  aIndexes as array dim sFind as string for x   1 to length aNames       if aNames x    sFind then y   x   y is then the index of the item in the array  then loop could be used to store these in an array also so instead of the above you would have   z   1 for x   1 to length aNames      if aNames x    sFind then          aIndexes z    x          z   z   1     endif

User · Answer

If you want an efficient search that is often repeated  first sort the array  Array Sort  and then use Array BinarySearch

User · Answer

In case you were looking for an older version of  NET then use   Module Module1      Sub Main           Dim arr   As String     ravi    Kumar    Ravi    Ramesh           Dim result As New List Of Integer          For i As Integer   0 To arr Length             If arr i  Contains  ra   Then result Add i          Next     End Sub  End Module

[vb.net] How can I search an array in VB.NET?

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