Filter Function (Visual Basic)

Artikel
11/16/2012

Returns a zero-based array containing a subset of a String array based on specified filter criteria.

Function Filter(
   ByVal Source() As { Object | String },
   ByVal Match As String,
   Optional ByVal Include As Boolean = True,
   Optional ByVal Compare As CompareMethod = CompareMethod.Binary
)  As String()

Parameters

Source
Required. One-dimensional array of strings to be searched.
Match
Required. String to search for.
Include
Optional. Boolean value indicating whether to return substrings that include or exclude Match. If Include is True, the Filter function returns the subset of the array that contains Match as a substring. If Include is False, the Filter function returns the subset of the array that does not contain Match as a substring.
Compare
Optional. Numeric value indicating the kind of string comparison to use. See "Settings" for values.

Settings

The Compare argument can have the following values.

Constant	Description
CompareMethod.Binary	Performs a binary comparison
CompareMethod.Text	Performs a textual comparison

Exceptions

Exception type	Error number	Condition
ArgumentException	9	Source is Nothing or is not a one-dimensional array.

See the "Error number" column if you are upgrading Visual Basic 6.0 applications that use unstructured error handling. (You can compare the error number against the Number Property (Err Object).) However, when possible, you should consider replacing such error control with Structured Exception Handling Overview for Visual Basic.

Remarks

If no matches of Match are found within Source, the Filter function returns an empty array. An error occurs if Source is set to Nothing or is not a one-dimensional array.

The array returned by the Filter function contains only enough elements to contain the number of matched items.

Example

This example demonstrates the use of the Filter function.

Dim TestStrings(2) As String
TestStrings(0) = "This"
TestStrings(1) = "Is"
TestStrings(2) = "It" 
Dim subStrings() As String 
' Returns ["This", "Is"].
subStrings = Filter(TestStrings, "is", True, CompareMethod.Text)
' Returns ["This"].
subStrings = Filter(TestStrings, "is", True, CompareMethod.Binary)
' Returns ["Is", "It"].
subStrings = Filter(TestStrings, "is", False, CompareMethod.Binary)

Requirements

Namespace:Microsoft.VisualBasic

**Module:**Strings

Assembly: Visual Basic Runtime Library (in Microsoft.VisualBasic.dll)

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