Bug #13833: String#scanf("%a") incorrectly requires a sign on the (binary) exponent

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.4.1p111 (2017-03-22 revision 58053) [x86_64-darwin16]
• Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN

[cabo (Carsten Bormann)]

>> Float("0x1p9")
=> 512.0
>> Float("0x1p+9")
=> 512.0
>> "0x1p+9".scanf("%a")
=> [512.0]
>> "0x1p9".scanf("%a")
=> [0.0]                              # Oops
>> RUBY_VERSION
=> "2.4.1"

In scanf.rb, there are three regexps that say the equivalent of [pP][+-] where they should say [pP][+-]?

[tarotaro0 (taro taro)]

Hi, cabo.

I implemented to fix this bug and created PR:

https://github.com/ruby/ruby/pull/1689

Could you please check this?

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset trunk|r60261.

---

Fix bug about String#scanf("%a")

• lib/scanf.rb (extract_float, initialize): allow to omit a sign
  on the binary exponent. [ruby-core:82435] [Bug #13833]
  [Fix GH-1689]

From: tarotaro0 [e-mail]