XLISP numberp

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# numberp

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

## Syntax

(numberp expr)
  expr - the expression to check
  returns - T if the expression is a number, NIL otherwise

## Description

The 'numberp' predicate function checks if an 'expr' is a number. T is returned if 'expr' is an integer or floating point number, NIL is returned otherwise.

## Examples

    (numberp 1)         ; returns T - integer
    (numberp 1.2)       ; returns T - float
    (numberp '1)        ; returns T - still an integer
    (numberp #x034)     ; returns T - the readmacro produces an integer

    (numberp 'a)        ; returns NIL - symbol
    (numberp #\a)       ; returns NIL - character
    (numberp NIL)       ; returns NIL - NIL
    (numberp #(0 1 2))  ; returns NIL - array

See the numberp predicate function in the XLISP 2.0 manual.

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