String.Split Method (String[], Int32, StringSplitOptions) (System)

.NET Framework Class Library

String..::.Split Method (array<String>[]()[], Int32, StringSplitOptions)

Returns a string array that contains the substrings in this string that are delimited by elements of a specified string array. Parameters specify the maximum number of substrings to return and whether to return empty array elements.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)

Syntax

Visual Basic (Declaration)

<ComVisibleAttribute(False)> _
Public Function Split ( _
    separator As String(), _
    count As Integer, _
    options As StringSplitOptions _
) As String()

Visual Basic (Usage)

Dim instance As String
Dim separator As String()
Dim count As Integer
Dim options As StringSplitOptions
Dim returnValue As String()

returnValue = instance.Split(separator, _
    count, options)

[ComVisibleAttribute(false)]
public string[] Split(
    string[] separator,
    int count,
    StringSplitOptions options
)

Visual C++

[ComVisibleAttribute(false)]
public:
array<String^>^ Split(
    array<String^>^ separator, 
    int count, 
    StringSplitOptions options
)

JScript

public function Split(
    separator : String[], 
    count : int, 
    options : StringSplitOptions
) : String[]

Parameters

separator: Type: array<System..::.String>[]()[]
An array of strings that delimit the substrings in this string, an empty array that contains no delimiters, or nullNothingnullptra null reference (Nothing in Visual Basic).

count: Type: System..::.Int32
The maximum number of substrings to return.

options: Type: System..::.StringSplitOptions
Specify RemoveEmptyEntries to omit empty array elements from the array returned, or None to include empty array elements in the array returned.

Return Value

Type: array<System..::.String>[]()[]
An array whose elements contain the substrings in this string that are delimited by one or more strings in separator. For more information, see the Remarks section.

Exceptions

Exception	Condition
ArgumentOutOfRangeException	count is negative.
ArgumentException	options is not one of the StringSplitOptions values.

Remarks

Return Value Details

Delimiter strings are not included in the elements of the returned array.

If this instance does not contain any of the strings in separator, or the count parameter is 1, the returned array consists of a single element that contains this instance. If the separator parameter is nullNothingnullptra null reference (Nothing in Visual Basic) or contains no characters, white-space characters are assumed to be the delimiters. For a list of the characters that the Split method interprets as white space, see the table in the Remarks section of the String..::.Split(array<Char>[]()[]) method. (Note that this list is slightly different from the list of white-space characters recognized by the Trim()()() method.)

If the count parameter is zero, or the options parameter is RemoveEmptyEntries and the length of this instance is zero, an empty array is returned.

Each element of separator defines a separate delimiter character. If the options parameter is None, and two delimiters are adjacent or a delimiter is found at the beginning or end of this instance, the corresponding array element contains Empty.

If there are more than count substrings in this instance, the first count minus 1 substrings are returned in the first count minus 1 elements of the return value, and the remaining characters in this instance are returned in the last element of the return value.

If count is greater than the number of substrings, the available substrings are returned and no exception is thrown.

Comparison Details

The Split method extracts the substrings in this string that are delimited by one or more of the strings in the separator parameter, and returns those substrings as elements of an array.

The Split method looks for delimiters by performing comparisons using case-sensitive ordinal sort rules. For more information about word, string, and ordinal sorts, see the System.Globalization..::.CompareOptions enumeration.

The Split method ignores any element of separator whose value is nullNothingnullptra null reference (Nothing in Visual Basic) or the empty string ("").

To avoid ambiguous results when strings in separator have characters in common, the Split method proceeds from the beginning to the end of the value of the instance, and matches the first element in separator that is equal to a delimiter in the instance. The order in which substrings are encountered in the instance takes precedence over the order of elements in separator.

For example, consider an instance whose value is "abcdef". If the first element in separator was "ef" and the second element was "bcde", the result of the split operation would be "a" and "f". This is because the substring in the instance, "bcde", is encountered and matches an element in separator before the substring "f" is encountered.

However, if the first element of separator was "bcd" and the second element was "bc", the result of the split operation would be "a" and "ef". This is because "bcd" is the first delimiter in separator that matches a delimiter in the instance. If the order of the separators was reversed so the first element was "bc" and the second element was "bcd", the result would be "a" and "def".

Performance Considerations

The Split methods allocate memory for the returned array object and a String object for each array element. If your application requires optimal performance or if managing memory allocation is critical in your application, consider using the IndexOf or IndexOfAny method, and optionally the Compare method, to locate a substring within a string.

If you are splitting a string at a separator character, use the IndexOf or IndexOfAny method to locate a separator character in the string. If you are splitting a string at a separator string, use the IndexOf or IndexOfAny method to locate the first character of the separator string. Then use the Compare method to determine whether the characters after that first character are equal to the remaining characters of the separator string.

In addition, if the same set of characters is used to split strings in multiple Split method calls, consider creating a single array and referencing it in each method call. This significantly reduces the additional overhead of each method call.

Examples

The following example uses the StringSplitOptions enumeration to include or exclude substrings generated by the Split method.

Visual Basic

' This example demonstrates the String() methods that use
' the StringSplitOptions enumeration.
Imports System

Class Sample
    Public Shared Sub Main() 
        Dim s1 As String = ",ONE,,TWO,,,THREE,,"
        Dim s2 As String = "[stop]" & _
                           "ONE[stop][stop]" & _
                           "TWO[stop][stop][stop]" & _
                           "THREE[stop][stop]"
        Dim charSeparators() As Char = {","c}
        Dim stringSeparators() As String = {"[stop]"}
        Dim result() As String
        ' ------------------------------------------------------------------------------
        ' Split a string delimited by characters.
        ' ------------------------------------------------------------------------------
        Console.WriteLine("1) Split a string delimited by characters:" & vbCrLf)

        ' Display the original string and delimiter characters.
        Console.WriteLine("1a )The original string is ""{0}"".", s1)
        Console.WriteLine("The delimiter character is '{0}'." & vbCrLf, charSeparators(0))

        ' Split a string delimited by characters and return all elements.
        Console.WriteLine("1b) Split a string delimited by characters and " & _
                          "return all elements:")
        result = s1.Split(charSeparators, StringSplitOptions.None)
        Show(result)

        ' Split a string delimited by characters and return all non-empty elements.
        Console.WriteLine("1c) Split a string delimited by characters and " & _
                          "return all non-empty elements:")
        result = s1.Split(charSeparators, StringSplitOptions.RemoveEmptyEntries)
        Show(result)

        ' Split the original string into the string and empty string before the 
        ' delimiter and the remainder of the original string after the delimiter.
        Console.WriteLine("1d) Split a string delimited by characters and " & _
                          "return 2 elements:")
        result = s1.Split(charSeparators, 2, StringSplitOptions.None)
        Show(result)

        ' Split the original string into the string after the delimiter and the 
        ' remainder of the original string after the delimiter.
        Console.WriteLine("1e) Split a string delimited by characters and " & _
                          "return 2 non-empty elements:")
        result = s1.Split(charSeparators, 2, StringSplitOptions.RemoveEmptyEntries)
        Show(result)

        ' ------------------------------------------------------------------------------
        ' Split a string delimited by another string.
        ' ------------------------------------------------------------------------------
        Console.WriteLine("2) Split a string delimited by another string:" & vbCrLf)

        ' Display the original string and delimiter string.
        Console.WriteLine("2a) The original string is ""{0}"".", s2)
        Console.WriteLine("The delimiter string is ""{0}""." & vbCrLf, stringSeparators(0))

        ' Split a string delimited by another string and return all elements.
        Console.WriteLine("2b) Split a string delimited by another string and " & _
                          "return all elements:")
        result = s2.Split(stringSeparators, StringSplitOptions.None)
        Show(result)

        ' Split the original string at the delimiter and return all non-empty elements.
        Console.WriteLine("2c) Split a string delimited by another string and " & _
                          "return all non-empty elements:")
        result = s2.Split(stringSeparators, StringSplitOptions.RemoveEmptyEntries)
        Show(result)

        ' Split the original string into the empty string before the 
        ' delimiter and the remainder of the original string after the delimiter.
        Console.WriteLine("2d) Split a string delimited by another string and " & _
                          "return 2 elements:")
        result = s2.Split(stringSeparators, 2, StringSplitOptions.None)
        Show(result)

        ' Split the original string into the string after the delimiter and the 
        ' remainder of the original string after the delimiter.
        Console.WriteLine("2e) Split a string delimited by another string and " & _
                          "return 2 non-empty elements:")
        result = s2.Split(stringSeparators, 2, StringSplitOptions.RemoveEmptyEntries)
        Show(result)

    End Sub 'Main


    ' Display the array of separated strings.
    Public Shared Sub Show(ByVal entries() As String) 
        Console.WriteLine("The return value contains these {0} elements:", entries.Length)
        Dim entry As String
        For Each entry In  entries
            Console.Write("<{0}>", entry)
        Next entry
        Console.Write(vbCrLf & vbCrLf)

    End Sub 'Show
End Class 'Sample
'
'This example produces the following results:
'
'1) Split a string delimited by characters:
'
'1a )The original string is ",ONE,,TWO,,,THREE,,".
'The delimiter character is ','.
'
'1b) Split a string delimited by characters and return all elements:
'The return value contains these 9 elements:
'<><ONE><><TWO><><><THREE><><>
'
'1c) Split a string delimited by characters and return all non-empty elements:
'The return value contains these 3 elements:
'<ONE><TWO><THREE>
'
'1d) Split a string delimited by characters and return 2 elements:
'The return value contains these 2 elements:
'<><ONE,,TWO,,,THREE,,>
'
'1e) Split a string delimited by characters and return 2 non-empty elements:
'The return value contains these 2 elements:
'<ONE><TWO,,,THREE,,>
'
'2) Split a string delimited by another string:
'
'2a) The original string is "[stop]ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]".
'The delimiter string is "[stop]".
'
'2b) Split a string delimited by another string and return all elements:
'The return value contains these 9 elements:
'<><ONE><><TWO><><><THREE><><>
'
'2c) Split a string delimited by another string and return all non-empty elements:
'The return value contains these 3 elements:
'<ONE><TWO><THREE>
'
'2d) Split a string delimited by another string and return 2 elements:
'The return value contains these 2 elements:
'<><ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]>
'
'2e) Split a string delimited by another string and return 2 non-empty elements:
'The return value contains these 2 elements:
'<ONE><TWO[stop][stop][stop]THREE[stop][stop]>
'

// This example demonstrates the String() methods that use
// the StringSplitOptions enumeration.
using System;

class Sample 
{
    public static void Main() 
    {
    string s1 = ",ONE,,TWO,,,THREE,,";
    string s2 = "[stop]" +
                "ONE[stop][stop]" +
                "TWO[stop][stop][stop]" +
                "THREE[stop][stop]";
    char[] charSeparators = new char[] {','};
    string[] stringSeparators = new string[] {"[stop]"};
    string[] result;
// ------------------------------------------------------------------------------
// Split a string delimited by characters.
// ------------------------------------------------------------------------------
    Console.WriteLine("1) Split a string delimited by characters:\n");

// Display the original string and delimiter characters.
    Console.WriteLine("1a )The original string is \"{0}\".", s1);
    Console.WriteLine("The delimiter character is '{0}'.\n", 
                       charSeparators[0]);

// Split a string delimited by characters and return all elements.
    Console.WriteLine("1b) Split a string delimited by characters and " +
                      "return all elements:");
    result = s1.Split(charSeparators, StringSplitOptions.None);
    Show(result);

// Split a string delimited by characters and return all non-empty elements.
    Console.WriteLine("1c) Split a string delimited by characters and " +
                      "return all non-empty elements:");
    result = s1.Split(charSeparators, StringSplitOptions.RemoveEmptyEntries);
    Show(result);

// Split the original string into the string and empty string before the 
// delimiter and the remainder of the original string after the delimiter.
    Console.WriteLine("1d) Split a string delimited by characters and " +
                      "return 2 elements:");
    result = s1.Split(charSeparators, 2, StringSplitOptions.None);
    Show(result);

// Split the original string into the string after the delimiter and the 
// remainder of the original string after the delimiter.
    Console.WriteLine("1e) Split a string delimited by characters and " +
                      "return 2 non-empty elements:");
    result = s1.Split(charSeparators, 2, StringSplitOptions.RemoveEmptyEntries);
    Show(result);

// ------------------------------------------------------------------------------
// Split a string delimited by another string.
// ------------------------------------------------------------------------------
    Console.WriteLine("2) Split a string delimited by another string:\n");

// Display the original string and delimiter string.
    Console.WriteLine("2a) The original string is \"{0}\".", s2);
    Console.WriteLine("The delimiter string is \"{0}\".\n", stringSeparators[0]);

// Split a string delimited by another string and return all elements.
    Console.WriteLine("2b) Split a string delimited by another string and " +
                      "return all elements:");
    result = s2.Split(stringSeparators, StringSplitOptions.None);
    Show(result);

// Split the original string at the delimiter and return all non-empty elements.
    Console.WriteLine("2c) Split a string delimited by another string and " +
                      "return all non-empty elements:");
    result = s2.Split(stringSeparators, StringSplitOptions.RemoveEmptyEntries);
    Show(result);

// Split the original string into the empty string before the 
// delimiter and the remainder of the original string after the delimiter.
    Console.WriteLine("2d) Split a string delimited by another string and " +
                      "return 2 elements:");
    result = s2.Split(stringSeparators, 2, StringSplitOptions.None);
    Show(result);

// Split the original string into the string after the delimiter and the 
// remainder of the original string after the delimiter.
    Console.WriteLine("2e) Split a string delimited by another string and " + 
                      "return 2 non-empty elements:");
    result = s2.Split(stringSeparators, 2, StringSplitOptions.RemoveEmptyEntries);
    Show(result);
    }

// Display the array of separated strings.
    public static void Show(string[] entries)
    {
    Console.WriteLine("The return value contains these {0} elements:", entries.Length);
    foreach (string entry in entries)
        {
        Console.Write("<{0}>", entry);
        }
    Console.Write("\n\n");
    }
}
/*
This example produces the following results:

1) Split a string delimited by characters:

1a )The original string is ",ONE,,TWO,,,THREE,,".
The delimiter character is ','.

1b) Split a string delimited by characters and return all elements:
The return value contains these 9 elements:
<><ONE><><TWO><><><THREE><><>

1c) Split a string delimited by characters and return all non-empty elements:
The return value contains these 3 elements:
<ONE><TWO><THREE>

1d) Split a string delimited by characters and return 2 elements:
The return value contains these 2 elements:
<><ONE,,TWO,,,THREE,,>

1e) Split a string delimited by characters and return 2 non-empty elements:
The return value contains these 2 elements:
<ONE><TWO,,,THREE,,>

2) Split a string delimited by another string:

2a) The original string is "[stop]ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]".
The delimiter string is "[stop]".

2b) Split a string delimited by another string and return all elements:
The return value contains these 9 elements:
<><ONE><><TWO><><><THREE><><>

2c) Split a string delimited by another string and return all non-empty elements:
The return value contains these 3 elements:
<ONE><TWO><THREE>

2d) Split a string delimited by another string and return 2 elements:
The return value contains these 2 elements:
<><ONE[stop][stop]TWO[stop][stop][stop]THREE[stop][stop]>

2e) Split a string delimited by another string and return 2 non-empty elements:
The return value contains these 2 elements:
<ONE><TWO[stop][stop][stop]THREE[stop][stop]>

*/

Visual C++

// This example demonstrates the String.Split(Char[], Boolean) and 
//                               String.Split(Char[], Int32, Boolean) methods
using namespace System;
void Show( array<String^>^entries )
{
   Console::WriteLine( "The return value contains these {0} elements:", entries->Length );
   System::Collections::IEnumerator^ myEnum = entries->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      String^ entry = safe_cast<String^>(myEnum->Current);
      Console::Write( "<{0}>", entry );
   }

   Console::Write( "{0}{0}", Environment::NewLine );
}

int main()
{
   String^ s = ",one,,,two,,,,,three,,";
   array<Char>^sep = gcnew array<Char>{
      ','
   };
   array<String^>^result;

   //
   Console::WriteLine( "The original string is \"{0}\".", s );
   Console::WriteLine( "The separation character is '{0}'.", sep[ 0 ] );
   Console::WriteLine();

   //
   Console::WriteLine( "Split the string and return all elements:" );
   result = s->Split( sep, StringSplitOptions::None );
   Show( result );

   //
   Console::WriteLine( "Split the string and return all non-empty elements:" );
   result = s->Split( sep, StringSplitOptions::RemoveEmptyEntries );
   Show( result );

   //
   Console::WriteLine( "Split the string and return 2 elements:" );
   result = s->Split( sep, 2, StringSplitOptions::None );
   Show( result );

   //
   Console::WriteLine( "Split the string and return 2 non-empty elements:" );
   result = s->Split( sep, 2, StringSplitOptions::RemoveEmptyEntries );
   Show( result );
}

/*
This example produces the following results:

The original string is ",one,,,two,,,,,three,,".
The separation character is ','.

Split the string and return all elements:
The return value contains these 12 elements:
<><one><><><two><><><><><three><><>

Split the string and return all non-empty elements:
The return value contains these 3 elements:
<one><two><three>

Split the string and return 2 elements:
The return value contains these 2 elements:
<><one,,,two,,,,,three,,>

Split the string and return 2 non-empty elements:
The return value contains these 2 elements:
<one><,,two,,,,,three,,>

*/

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Version Information

.NET Framework

Supported in: 3.5, 3.0, 2.0

Reference