XLISP digit-char-p

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# digit-char-p

Type: | - | predicate function (subr)
Source: | - | xlstr.c

## Syntax

(digit-char-p char)
  char - a character expression
  returns - the digit weight if character is a digit, NIL otherwise

## Description

The 'digit-char-p' predicate function checks if the 'char' expression is a numeric digit. If 'char' is numeric digit, the equivalent integer value is returned, otherwise a NIL is returned. Decimal digits are '0' [ASCII decimal value 48] through '9' [ASCII decimal value 57].

## Examples

    (digit-char-p #\0)   ; returns 0
    (digit-char-p #\9)   ; returns 9
    (digit-char-p #\A)   ; returns NIL
    (digit-char-p #\a)   ; returns NIL
    (digit-char-p #\.)   ; returns NIL
    (digit-char-p #\-)   ; returns NIL
    (digit-char-p #\+)   ; returns NIL

Note: Other non-digit characters used in numbers are NOT included: plus [+], minus [-], exponent [e or E] and decimal point [.].

Common Lisp: Common Lisp supports the use of an optional radix parameter. This option specifies numeric base. This allows the 'digit-char-p' to function properly for hexadecimal digits [for example]. Common LISP supports up to base 36 radix systems. XLISP does not support this radix parameter.

See the digit-char-p predicate function in the XLISP 2.0 manual.

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Nyquist / XLISP 2.0 - Contents | Tutorials | Examples | Reference