From: "Wolfgang Nádasi-Donner" <ed.odanow@...>
Date: 2007-10-24T06:13:47+09:00
Subject: Re: Encoding::primary_encoding

I really don't understand what effects the primary encoding has on IO. The first 
tests show effect.

The program:
 >>>>> Program >>>>>
puts "Primary encoding: #{Encoding.primary_encoding}"

puts "*** bomdata.txt ***"
File.open('bomdata.txt', 'r') do |f|
   u = f.read
   puts "u.encoding:       #{u.encoding}"
   puts "u.length:         #{u.length}"
   puts "u.bytesize:       #{u.bytesize}"
   puts "Character values in string 'u':"
   u.each_char{|c|puts("%X" % c.ord)}
   puts "Character values in string 'u.force_encoding(UTF-8)':"
   u.force_encoding('UTF-8').each_char{|c|puts("%X" % c.ord)}
end

puts "*** nobomdata.txt ***"
File.open('nobomdata.txt', 'r') do |f|
   v = f.read
   puts "v.encoding:       #{v.encoding}"
   puts "v.length:         #{v.length}"
   puts "v.bytesize:       #{v.bytesize}"
   puts "Character values in string 'v':"
   v.each_char{|c|puts("%X" % c.ord)}
   puts "Character values in string 'v.force_encoding(UTF-8)':"
   v.force_encoding('UTF-8').each_char{|c|puts("%X" % c.ord)}
end>>>>> End of Program >>>>>

The protocol:
 >>>>> Protocol >>>>>
C:\Dokumente und Einstellungen\wolfgang\Desktop>ruby19 -v
ruby 1.9.0 (2007-10-23 patchlevel 0) [i386-mingw32]

C:\Dokumente und Einstellungen\wolfgang\Desktop>ruby19 utf8_bom_read.rb
Primary encoding: <Encoding:UTF-8>
*** bomdata.txt ***
u.encoding:       <Encoding:ASCII-8BIT>
u.length:         13
u.bytesize:       13
Character values in string 'u':
EF
BB
BF
40
CE
BB
E2
85
93
F0
9D
84
9E
Character values in string 'u.force_encoding(UTF-8)':
FEFF
40
3BB
2153
1D11E
*** nobomdata.txt ***
v.encoding:       <Encoding:ASCII-8BIT>
v.length:         10
v.bytesize:       10
Character values in string 'v':
40
CE
BB
E2
85
93
F0
9D
84
9E
Character values in string 'v.force_encoding(UTF-8)':
40
3BB
2153
1D11E
 >>>>> End of Protocol >>>>>

Wolfgang N��dasi-Donner