Introduction to Characters (ANSI and GNU Common Lisp Document)

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#### 13.1.1 Introduction to Characters

A character is an object that represents a unitary token (e.g., a letter, a special symbol, or a “control character”) in an aggregate quantity of text (e.g., a string or a text stream).

Common Lisp allows an implementation to provide support for international language characters as well as characters used in specialized arenas (e.g., mathematics).

The following figures contain lists of defined names applicable to characters.

Figure 13–1 lists some defined names relating to character attributes and character predicates.

      alpha-char-p     char-not-equal     char>
      alphanumericp    char-not-greaterp  char>=
      both-case-p      char-not-lessp     digit-char-p
      char-code-limit  char/=             graphic-char-p
      char-equal       char<              lower-case-p
      char-greaterp    char<=             standard-char-p
      char-lessp       char=              upper-case-p

           Figure 13–1: Character defined names – 1

Figure 13–2 lists some character construction and conversion defined names.

      char-code      char-name    code-char
      char-downcase  char-upcase  digit-char
      char-int       character    name-char

      Figure 13–2: Character defined names – 2