Strings

Overview

Strings are sequences of characters. Strings are written as sequences of characters enclosed within quotation marks (“).

The length of a string is the number of characters that it contains. This number is an exact, non-negative integer that is fixed when the string is created. The valid indexes of a string are the exact non-negative integers less than the length of the string. The first character of a string has index 0, the second has index 1, and so on.

Some of the procedures that operate on strings ignore the difference between upper and lower case. The names of the versions that ignore case end with “-ci” (for “case insensitive”).

(string-upcase string)

Returns a new string with all alphabetic characters in string converted to uppercase.

Parameters:

string (string) – The string to convert.

Returns:

A new, uppercased string.

Return type:

string

Example:

--> (string-upcase "Hello World")
  "HELLO WORLD"

(string-downcase string)

Returns a new string with all alphabetic characters in string converted to lowercase.

Parameters:

string (string) – The string to convert.

Returns:

A new, downcased string.

Return type:

string

Example:

--> (string-downcase "Hello World")
  "hello world"

(string-foldcase string)

Returns a new string with all characters in string converted to their folded-case equivalents. This is the preferred method for preparing strings for case-insensitive comparison.

Parameters:

string (string) – The string to convert.

Returns:

A new, case-folded string.

Return type:

string

Example:

--> (string-foldcase "Der Fluß")
  "der fluss"