How do I get the length of a string in EK9?

← Common String Operations · Ref: Q170

EK9 provides two ways to get string length and a dedicated empty check.

LENGTH OPERATOR

Prefix operator syntax:

  len <- length myString

Returns the number of characters.

METHOD SYNTAX

  len <- myString.length()

Equivalent to the operator form.

EMPTY CHECK

Test whether a string has no characters:

  if myString is empty
    stdout.println("No content")

Note: an empty string (length 0) IS set. An unset string is different from an empty string.

See Q37 for comprehensive string operations. See Q29 for the distinction between empty and unset. See Q242 for conversion and introspection operators including length.

Example

defines module qa.stringops.length

  defines program
    StringLengthDemo()
      stdout <- Stdout()

      greeting <- "Hello World"

      // === LENGTH OPERATOR ===

      len1 <- length greeting
      stdout.println(`Length (operator): ${len1}`)

      // === METHOD SYNTAX ===

      len2 <- greeting.length()
      stdout.println(`Length (method): ${len2}`)

      // === EMPTY CHECK ===

      emptyStr <- ""
      stdout.println(`Empty string length: ${length emptyStr}`)
      stdout.println(`Is empty: ${emptyStr is empty}`)

      // Empty string IS set (not unset)
      require emptyStr?
      stdout.println(`Empty string isSet: ${emptyStr?}`)

      // Non-empty check
      if ~greeting is empty
        stdout.println("Greeting has content")

      // === UNSET STRING ===

      unsetStr <- String()
      stdout.println(`Unset string isSet: ${unsetStr?}`)

Common mistakes

E50060 — String has no size() method. Use the length prefix operator or .length() method. See ek9 -h E50060 for details.

Incorrect:

len1 <- greeting.size()

Correct:

len1 <- length greeting

Other ways to ask this

How do I count the characters in a string in EK9?
What is the EK9 equivalent of string.length()?
How do I check if a string is empty in EK9?

Coming from another language?

Java: str.length(), str.isEmpty(). Python: len(str), not str for empty check. Rust: str.len(), str.is_empty(). Go: len(str). JavaScript: str.length property. Kotlin: str.length, str.isEmpty(). EK9: length str or str.length(), str is empty.

Keywords: length, string, empty, count, characters, text, size