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String.Split Method (String[], StringSplitOptions)

 

Splits a string into substrings based on the strings in an array. You can specify whether the substrings include empty array elements.

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

[<ComVisibleAttribute(false)>]
member Split : 
        separator:string[] *
        options:StringSplitOptions -> string[]

Parameters

separator
Type: System.String[]

A string array that delimits the substrings in this string, an empty array that contains no delimiters, or null.

options
Type: System.StringSplitOptions

StringSplitOptions.RemoveEmptyEntries to omit empty array elements from the array returned; or StringSplitOptions.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 strings in separator. For more information, see the Remarks section.

Exception Condition
ArgumentException

options is not one of the StringSplitOptions values.

When a string is delimited by a known set of strings, you can use the Split method to separate it into substrings.

Delimiter strings are not included in the elements of the returned array. For example, if the separator array includes the string "--" and the value of the current string instance is "aa--bb-cc", the method returns an array that contains three elements: "aa", "bb", and "cc".

If this instance does not contain any of the strings in separator, the returned array consists of a single element that contains this instance.

If the options parameter is RemoveEmptyEntries and the length of this instance is zero, the method returns an empty array.

Each element of separator defines a separate delimiter that consists of one or more characters. If the options argument 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 String.Empty. For example, if separator includes two elements, "-" and "_", the value of the string instance is "-_aa-_", and the value of the options argument is None, the method returns a sting array with the following five elements:

  1. String.Empty, which represents the empty string that precedes the "-" substring at index 0.

  2. String.Empty, which represents the empty string between the "-" substring at index 0 and the "_" substring at index 1.

  3. "aa",

  4. String.Empty, which represents the empty string that follows the "_" substring at index 4.

  5. String.Empty, which represents the empty string that follows the "-" substring at index 5.

If any of the elements in separator consists of multiple characters, the entire substring is considered a delimiter. For example, if one of the elements in separator is "10", attempting to split the string "This10is10a10string." returns the following four-element array: { "This", "is", "a", "string." }.

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.

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.

No code example is currently available or this language may not be supported.

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 null or the empty string ("").

To avoid ambiguous results when strings in separator have characters in common, the Split operation 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 string array that contains two elements, "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 string array that contains two elements, "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 string array that contains two elements, "a" and "def".

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 illustrates the difference in the arrays returned by calling a string's String.Split(String[], StringSplitOptions) method with its options parameter equal to StringSplitOptions.None and StringSplitOptions.RemoveEmptyEntries.

No code example is currently available or this language may not be supported.

The following example defines an array of separators that include punctuation and white-space characters. Passing this array along with a value of StringSplitOptions.RemoveEmptyEntries to the Split(String[], StringSplitOptions) method returns an array that consists of the individual words from the string.

No code example is currently available or this language may not be supported.

Note that the method is called with the options argument set to StringSplitOptions.RemoveEmptyEntries. This prevents the returned array from includingString.Empty values that represent empty substring matches between punctuation marks and white-space characters.

Universal Windows Platform
Available since 8
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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