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char-code-limit

char-code-limit Constant Variable

Constant Value:

A non-negative integer , the exact magnitude of which is implementation-dependent, but which is not less than 96 (the number of standard characters).

Description:

The upper exclusive bound on the value returned by the function char-code.

See Also:

char-code

Notes:

The value of char-code-limit might be larger than the actual number of characters supported by the implementation.

char-name

Expanded Reference: char-code-limit​

The upper bound on character codes​

char-code-limit is a constant that gives the upper exclusive bound on values returned by char-code. Its exact value is implementation-dependent but is at least 96.

(integerp char-code-limit)
=> T
(>= char-code-limit 96)
=> T

All character codes are below char-code-limit​

The value returned by char-code for any character is always a non-negative integer strictly less than char-code-limit.

(< (char-code #\A) char-code-limit)
=> T
(< (char-code #\Space) char-code-limit)
=> T
(< (char-code #\z) char-code-limit)
=> T

Iterating over all possible character codes​

char-code-limit can be used to enumerate all characters supported by the implementation. Note that not every code below the limit necessarily maps to a character.

;; Count how many valid characters exist
(loop for code from 0 below char-code-limit
      count (code-char code))
;; => implementation-dependent

;; Collect all standard characters by iterating codes
(length (loop for code from 0 below char-code-limit
              for ch = (code-char code)
              when (and ch (standard-char-p ch))
              collect ch))
=> 96

Typical values​

In most modern implementations using Unicode, char-code-limit is 1114112 (the number of Unicode code points). In simpler implementations it might be 256 or 128.

;; Just inspecting the value (implementation-dependent):
char-code-limit
=> 1114112