String#chop chops last byte, not char

Ruby
1

This is happening in ruby 1.8.6:

% ruby --version
ruby 1.8.6 (2007-09-23 patchlevel 110) [i686-darwin9.1.0]

Documentation says:

% ri String#chop
…Returns a new +String+ with the last character removed. If…

This is irb and Rails script/console sessions:

% ./script/console
Loading development environment (Rails 2.0.2)

“абвгд”.chop
=> “абвг\320”

“абвгд”.chop.chop
=> “абвг”

% irb

“абвгд”.chop
=> “\320\260\320\261\320\262\320\263\320”

“д”.chop
=> “\320”

“д”.chop.chop
=> “”

As you can see chop removes last byte vs last char. Btw, problem
happened while stuffing strings into legacy (ms sql server) db,
varchar(255) column. I came up with the following method (see below).
Maybe there is an easier alternative?

def truncate(text, size = 254, suffix = “…”)
if text.nil? then return end
l = size - suffix.size
if text.size > size
truncated_text = “”
text.each_char do |c|
if truncated_text.size + c.size < l
truncated_text << c
else
break
end
end
truncated_text += suffix
else
text
end
end

I did not report this as a bug, since I am not sure who is supposed to
be right - ruby or documentation.

2

On Wed, 23 Apr 2008 15:35:11 -0500, Evgeni Belin wrote:

This is happening in ruby 1.8.6:

% ruby --version
ruby 1.8.6 (2007-09-23 patchlevel 110) [i686-darwin9.1.0]

“д”.chop
=> “\320”

“д”.chop.chop
=> “”

As you can see chop removes last byte vs last char. Btw, problem

Ruby 1.8 does not have multi-byte character support built in, so it
assumes each character is one byte. If you would like unicode support,
include in your scripts

$KCODE=‘u’
require ‘jcode’

Then chop will work properly. (Though I’m not sure everything will be
perfect)

Ruby 1.9 has unicode support built in and handles this properly out of
the box.

3

Evgeni Belin wrote:

This is happening in ruby 1.8.6:

In Ruby 1.8.6, character == byte basically everywhere. You’ll need to
use a regex to remove the last character safely (UTF-8).

  • Charlie