Split Function (Visual Basic)

Artykuł
11/16/2012

Returns a zero-based, one-dimensional array containing a specified number of substrings.

Function Split(
   ByVal Expression As String,
   Optional ByVal Delimiter As String = " ",
   Optional ByVal Limit As Integer = -1,
   Optional ByVal Compare As CompareMethod = CompareMethod.Binary
) As String()

Parameters

Expression
Required. String expression containing substrings and delimiters.
Delimiter
Optional. Any string of characters used to identify substring limits. If Delimiter is omitted, the space character (" ") is assumed to be the delimiter.
Limit
Optional. Maximum number of substrings into which the input string should be split. The default, –1, indicates that the input string should be split at every occurrence of the Delimiter string.
Compare
Optional. Numeric value indicating the comparison to use when evaluating substrings. See "Settings" for values.

Returns

String array. If Expression is a zero-length string (""), Split returns a single-element array containing a zero-length string. If Delimiter is a zero-length string, or if it does not appear anywhere in Expression, Split returns a single-element array containing the entire Expression string.

Settings

The Compare argument can have the following values.

Constant	Description	Value
CompareMethod.Binary	Performs a binary comparison	0
CompareMethod.Text	Performs a textual comparison	1

Remarks

By default, or when Limit equals -1, the Split function splits the input string at every occurrence of the delimiter string, and returns the substrings in an array. When the Limit parameter is greater than zero, the Split function splits the string at the first Limit-1 occurrences of the delimiter, and returns an array with the resulting substrings. For example, Split("a:b:c", ":") returns the array {"a", "b", "c"}, while Split("a:b:c", ":", 2) returns the array {"a", "b:c"}.

When the Split function encounters two delimiters in a row, or a delimiter at the beginning or end of the string, it interprets them as surrounding an empty string (""). For example, Split("xx", "x") returns the array containing three empty strings: one from between the beginning of the string and the first "x", one from between the two "x" strings, and one from between the last "x" and the end of the string.

This table demonstrates how the optional Delimiter, Limit, and Compare parameters can change the behavior of the Split function.

Split Call	Return Value
Split("42, 12, 19")	{"42," , "12," , "19"}
Split("42, 12, 19", ", ")	{"42", "12", "19"}
Split("42, 12, 19", ", ", 2)	{"42", "12, 19"}
Split("192.168.0.1", ".")	{"192", "168", "0", "1"}
Split("Alice and Bob", " AND ")	{"Alice and Bob"}
Split("Alice and Bob", " AND ", ,CompareMethod.Text)	{"Alice", "Bob"}
Split("someone@example.com", "@",1)	{"someone@example.com"}
Split("someone@example.com", "@",2)	{"someone", "example.com"}

Example

The following example demonstrates how to split a string at its spaces.

Dim TestString As String = "Look at these!" 
' Returns an array containing "Look", "at", and "these!". 
Dim TestArray() As String = Split(TestString)

The following example demonstrates how to split strings with multiple delimiters in a row and filter out the empty strings.

Dim TestString As String = "apple    pear banana  " 
Dim TestArray() As String = Split(TestString)
' TestArray holds {"apple", "", "", "", "pear", "banana", "", ""} 
Dim LastNonEmpty As Integer = -1
For i As Integer = 0 To TestArray.Length - 1
    If TestArray(i) <> "" Then
        LastNonEmpty += 1
        TestArray(LastNonEmpty) = TestArray(i)
    End If 
Next 
ReDim Preserve TestArray(LastNonEmpty)
' TestArray now holds {"apple", "pear", "banana"}

Requirements

Namespace:Microsoft.VisualBasic

**Module:**Strings

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

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