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String.Split Method (Char[], StringSplitOptions)

Returns a string array that contains the substrings in this string that are delimited by elements of a specified Unicode character array. A parameter specifies whether to return empty array elements.

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

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

Parameters

separator
Type: System.Char[]

An array of Unicode characters that delimit the substrings in this string, an empty array that contains no delimiters, or null.

options
Type: System.StringSplitOptions

RemoveEmptyEntries to omit empty array elements from the array returned; or None to include empty array elements in the array returned.

Return Value

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

ExceptionCondition
ArgumentException

options is not one of the StringSplitOptions values.

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

If this instance does not contain any of the characters in separator, the returned array consists of a single element that contains this instance. If the separator parameter is null or contains no characters, white-space characters are assumed to be the delimiters. White-space characters are defined by the Unicode standard and return true if they are passed to the Char.IsWhiteSpace method. However, if the separator parameter in the call to this method overload is null, compiler overload resolution fails. To unambiguously identify the called method, your code must indicate the type of the null. The following example shows several ways to unambiguously identify this overload.

string phrase = "The quick  brown fox";
string[] words;

words = phrase.Split(default(Char[]), StringSplitOptions.RemoveEmptyEntries);

words = phrase.Split((char[]) null, StringSplitOptions.RemoveEmptyEntries);

words = phrase.Split(null as char[], StringSplitOptions.RemoveEmptyEntries);

Each element of separator defines a separate delimiter character. If the options parameter is RemoveEmptyEntries and the length of this instance is zero, an empty array is returned.

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.

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.

Notes to Callers

In the .NET Framework 3.5 and earlier versions, if the Split method is passed a separator that is null or contains no characters, the method uses a slightly different set of characters to split the string than the Trim method does to trim the string. In the .NET Framework 4, both methods use an identical set of Unicode white-space characters.

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

// 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]>

*/

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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