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/ Numbers Dictionary abs
Function

1+, 1-

1 + ⇒ number successor 1 - ⇒ number predecessor

Arguments and Values

numbera number.
successor, predecessora 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.

Backlinks

incf, decf, Numbers Dictionary, Numeric Operations, Symbols in the COMMON-LISP Package, Value Accumulation Clauses