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Split strings into substrings in C#

Tip

This article is part of the Fundamentals section for developers who already know at least one programming language and are learning C#. If you're new to programming, start with the Get started tutorials first.

Coming from another language? string.Split is C#'s counterpart to Java's String.split and JavaScript's String.prototype.split. Unlike those languages, C# returns an array (string[]), not a list, and the separator argument is a character or string, not a regular expression. For pattern-based splitting, see Regex.Split.

The String.Split method breaks a string into an array of substrings using one or more separators. It's the simplest way to parse delimited text such as words, CSV-style values, or protocol tokens.

The method has many overloads, but they cover four independent decisions:

  • Separators: one char, an array of char, one string, or an array of string.
  • Maximum result count: cap the number of substrings returned.
  • Empty-entry handling: keep empty substrings (the default) or drop them with StringSplitOptions.RemoveEmptyEntries.
  • Whitespace handling: trim leading and trailing whitespace from each entry with StringSplitOptions.TrimEntries.

Split a string into words

To split a phrase on whitespace, pass ' ' as the separator:

string phrase = "The quick brown fox jumps over the lazy dog.";
string[] words = phrase.Split(' ');

foreach (var word in words)
{
    Console.WriteLine($"<{word}>");
}
// => <The>
// => <quick>
// => <brown>
// => <fox>
// => <jumps>
// => <over>
// => <the>
// => <lazy>
// => <dog.>

Iterate the returned array with for to recover the position of each word:

string phrase = "The quick brown fox jumps over the lazy dog.";
string[] words = phrase.Split(' ');

for (int i = 0; i < words.Length; i++)
{
    Console.WriteLine($"Index {i}: <{words[i]}>");
}
// => Index 0: <The>
// => Index 1: <quick>
// => Index 2: <brown>
// => ...

If the input contains repeated instances of the separator character, Split produces empty entries, one for each "gap" between consecutive separators:

string phrase = "The quick brown    fox     jumps over the lazy dog.";
string[] words = phrase.Split(' ');

foreach (var word in words)
{
    Console.WriteLine($"<{word}>");
}
// The runs of spaces produce empty entries:
// => <The>
// => <quick>
// => <brown>
// => <>
// => <>
// => <>
// => <fox>
// => ...

Pass StringSplitOptions.RemoveEmptyEntries to drop those empty entries, as shown later in this article.

Split on multiple separator characters

When more than one character can act as a separator, pass them as an array. The following example treats spaces, commas, periods, colons, and tabs all as word boundaries:

char[] delimiters = [' ', ',', '.', ':', '\t'];

string text = "one\ttwo three:four,five six seven";
Console.WriteLine($"Original text: '{text}'");

string[] words = text.Split(delimiters);
Console.WriteLine($"{words.Length} words in text:");

foreach (var word in words)
{
    Console.WriteLine($"<{word}>");
}
// => 7 words in text:
// => <one>
// => <two>
// => <three>
// => <four>
// => <five>
// => <six>
// => <seven>

Adjacent separators still produce empty entries:

char[] delimiters = [' ', ',', '.', ':', '\t'];

string text = "one\ttwo :,five six seven";
Console.WriteLine($"Original text: '{text}'");

string[] words = text.Split(delimiters);
Console.WriteLine($"{words.Length} words in text:");

foreach (var word in words)
{
    Console.WriteLine($"<{word}>");
}
// => 7 words in text:
// => <one>
// => <two>
// => <>
// => <>
// => <five>
// => <six>
// => <seven>

Split on multicharacter separators

To split on whole-word or multicharacter separators, pass an array of strings. The string-array overloads require a StringSplitOptions value. Use RemoveEmptyEntries when repeated separators would otherwise produce empty results:

string[] separators = ["<<", "..."];

string text = "one<<two......three<four";
Console.WriteLine($"Original text: '{text}'");

string[] words = text.Split(separators, StringSplitOptions.RemoveEmptyEntries);
Console.WriteLine($"{words.Length} substrings in text:");

foreach (var word in words)
{
    Console.WriteLine(word);
}
// => 3 substrings in text:
// => one
// => two
// => three<four

Limit how many substrings you get back

Pass a count argument to cap the number of results. The final entry holds everything that's left, including any remaining separators:

string phrase = "The quick brown fox jumps over the lazy dog.";
string[] words = phrase.Split(' ', 4, StringSplitOptions.None);

foreach (var word in words)
{
    Console.WriteLine($"<{word}>");
}
// => <The>
// => <quick>
// => <brown>
// => <fox jumps over the lazy dog.>

This pattern is handy for key=value pairs and other formats where only the first separator is meaningful.

Trim whitespace from each entry

StringSplitOptions.TrimEntries strips leading and trailing whitespace from every returned substring. You can combine it with RemoveEmptyEntries for typical CSV-style cleanup:

string numerals = "1, 2, 3, 4, 5, 6, 7, 8, 9, 10";
string[] trimmed = numerals.Split(',', StringSplitOptions.TrimEntries);

Console.WriteLine("Trimmed entries:");
foreach (var word in trimmed)
{
    Console.WriteLine($"<{word}>");
}

string[] untrimmed = numerals.Split(',', StringSplitOptions.None);
Console.WriteLine("Untrimmed entries:");
foreach (var word in untrimmed)
{
    Console.WriteLine($"<{word}>");
}
// => Trimmed entries: <1> <2> ... <10>
// => Untrimmed entries: <1> < 2> ... < 10>

Use regular expressions

Split works well for fixed character or string delimiters. For pattern-based splitting, use Regex.Split. For an introduction to regular expressions on strings, see String operations.

See also

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