0004553: Num.num_of_string should accept decimal numbers

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Date Submitted

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0004553

OCaml

OCaml general

public

2008-05-08 15:02

2008-08-04 17:21

Reporter

zack

Assigned To

Priority

normal

Severity

feature

Reproducibility

always

Status

acknowledged

Resolution

open

Platform

OS Version

Product Version

3.10.1

Target Version

Fixed in Version

Summary

0004553: Num.num_of_string should accept decimal numbers

Description

It seems that Num.num_of_string works only on strings denoting integers:

# Num.num_of_string "1.5";;
Exception: Failure "num_of_string".

Supporting decimal numbers appears to be quite easy: numbers such as "1.5" can be mapped to the Ratio.ratio "15/10" and then injected to Num using the Num.Ratio constructor. The change will be backward compatible as the new functionality can be triggered only when the input string contain a '.', situation which currently raise the Failure above.

Can you please consider adding support for decimal numbers in the Num.num_of_string function?

A sample implementation (relying on the current implementation of Num.num_of_string for integer strings) is reported below in the additional information section.

Cheers.

Additional Information

let my_num_of_string s =
  let dot_pos = try Some (String.index s '.') with Not_found -> None in
  match dot_pos with
  | None -> Num.num_of_string s
  | Some i -> (* e.g.: s = "45.6789", i = 2 *)
      let len = String.length s in
      let numerator = (* e.g. "45" ^ "6789" = "456789" *)
        String.sub s 0 i ^ String.sub s (i + 1) (len - (i + 1)) in
      let denominator = (* e.g. <big_int 10000> *)
        Big_int.power_int_positive_int 10 (len - (i + 1)) in
      Num.Ratio (Ratio.create_ratio (big_int_of_string numerator) denominator)

Issue History
Date Modified	Username	Field	Change
2008-05-08 15:02	zack	New Issue
2008-08-04 17:21	doligez	Severity	minor => feature
2008-08-04 17:21	doligez	Status	new => acknowledged
2008-08-04 17:21	doligez	Additional Information Updated

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