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Strings

Construction​

A string can be written inline between a single pair of double quotes or via a multi-line block between three pairs of double-quotes.

Inline​

An example of an inline string is "abc". A double quote can appear in an inline string by escaping it with \ as in "ab\"cd". Here is a list of some characters that can be expressed via escaping:

  • " via \",
  • a tab via \t,
  • a new line via \n, and
  • \ via \\.

Block​

Here is an example of a block string, which is defined using three pairs of double quotes.

myMultiLineString =
"""
This is the first line of my "string"
and this is the last line.
""";

where the text is interprated literally. In particular, all white space is included and all escape sequences are ignored.

Operations​

The following operations are available on strings.

  • length(x): the number of characters in a string. For example, length("abc") is 3.
  • x + y: the result of concatenating x and y. For example, "abc" + "def" evaluates to "abcdef".
  • matches(string, pattern): returns true if and only if pattern occurs in string, case-sensitive. For example, matches("def", "def") and matches("abcdefefg", "*def*") both return true.
  • substring(s, b, e): the substring of string s starting from index b (inclusive) and ending at index e ( exclusive). For example,substring("abcdef", 0, 6) is "abcdef", substring("abcdef", 1, 3) is "bc" (empty string), and substring("abcdef", 1, 1) is "".
  • prefix(s, n): the first n characters of string s. For example, prefix("abcdef", 3) is "abc" , prefix("abcdef", 0) is "" (empty string), and prefix("abcdef", 10) is "abcdef".
  • suffix(s, n): the last n characters of string s. For example, suffix("abcdef", 3) is "def" , suffix("abcdef", 0) is "" (empty string), and suffix("abcdef", 10) is "abcdef".
  • toUpperCase(x) and toLowerCase(x): respectively change all alphabetic characters in the string to upper- and lower-case. For example, toUpperCase("UpperCase") is "UPPERCASE" andtoLowerCase("LowerCase") is "lowercase".
  • replace(text, target, replacement): replaces every occurrence of target in text with replacement. All three arguments must be strings. For example, replace("abc-def", "-", "_") is "abc_def", replace("abc-def", "-", "") is "abcdef" and replace("abab", "a", "cd") is "cdbcdb".