Procedure: number->string
z
[radix
]
The procedure
number->string
takes a number and a radix and returns as a string an external representation of the given number in the given radix such that(let ((number number) (radix radix)) (eqv? number (string->number (number->string number radix) radix)))is true. It is an error if no possible result makes this expression true.
If present,
radix
must be an exact integer in the range 2 to 36, inclusive. If omitted,radix
defaults to 10.If
z
is inexact, theradix
is 10, and the above expression can be satisfied by a result that contains a decimal point, then the result contains a decimal point and is expressed using the minimum number of digits (exclusive of exponent and trailing zeroes) needed to make the above expression; otherwise the format of the result is unspecified.The result returned by
number->string
never contains an explicit radix prefix.Note: The error case can occur only when
z
is not a complex number or is a complex number with a non-rational real or imaginary part.Rationale: If
z
is an inexact number and theradix
is 10, then the above expression is normally satisfied by a result containing a decimal point. The unspecified case allows for infinities, NaNs, and unusual representations.
Procedure: string->number
string
[radix
]
Returns a number of the maximally precise representation expressed by the given
string
. It is an error ifradix
is not an exact integer in the range 2 to 26, inclusive.If supplied,
radix
is a default radix that will be overridden if an explicit radix prefix is present in the string (e.g."#o177"
). Ifradix
is not supplied, then the defaultradix
is 10. Ifstring
is not a syntactically valid notation for a number, or would result in a number that the implementation cannot represent, thenstring->number
returns#f
. An error is never signaled due to the content ofstring
.(string->number "100") ⇒ 100 (string->number "100" 16) ⇒ 256 (string->number "1e2") ⇒ 100.0 (string->number "#x100" 10) ⇒ 256