Apropos

1+, 1Function

    Syntax

    1+ number successor

    1number predecessor

    Arguments and Values

    number — a number.

    successor, predecessor — a number.

    Description

    1+ returns a number that is one more than its argument number. 1- returns a number that is one less than its argument number.

    Examples
    (1+ 99)  100 
    (1- 100)  99 
    (1+ (complex 0.0))  #C(1.0 0.0) 
    (1- 5/3)  2/3
    Exceptional Situations

    Might signal type-error if its argument is not a number. Might signal arithmetic-error.

    See Also

    incf, decf

    Notes
    (1+ number)  (+ number 1) 
    (1- number)  (- number 1)

    Implementors are encouraged to make the performance of both the previous expressions be the same.