chickadee » scheme » string->number

Returns a number of the maximally precise representation expressed by the given string. Radix must be an exact integer, either 2, 8, 10, or 16. If supplied, radix is a default radix that may be overridden by an explicit radix prefix in string (e.g. "#o177"). If radix is not supplied, then the default radix is 10. If string is not a syntactically valid notation for a number, then string->number returns #f.

(string->number "100")                ===>  100
(string->number "100" 16)             ===>  256
(string->number "1e2")                ===>  100.0
(string->number "15##")               ===>  1500.0

Note: The domain of string->number may be restricted by implementations in the following ways. String->number is permitted to return #f whenever string contains an explicit radix prefix. If all numbers supported by an implementation are real, then string-> number is permitted to return #f whenever string uses the polar or rectangular notations for complex numbers. If all numbers are integers, then string->number may return #f whenever the fractional notation is used. If all numbers are exact, then string->number may return #f whenever an exponent marker or explicit exactness prefix is used, or if a # appears in place of a digit. If all inexact numbers are integers, then string->number may return #f whenever a decimal point is used.