The errata list is a list of errors and their corrections that were found after the product was released. If the error was corrected in a later version or reprint the date of the correction will be displayed in the column titled "Date Corrected".
The following errata were submitted by our customers and approved as valid errors by the author or editor.
| Version |
Location |
Description |
Submitted By |
Date submitted |
Date corrected |
|
1
http://my.safaribooksonline.com/book/web-development/ruby/9780596529864/5dot-math/basic_math_operations |
what is clearly intended to be binary literals omit the '0b' prefix and are treated as decimal numbers. The results are correct for decimal numbers but not binary numbers. Seeing as how the section is supposed to be about binary math, I view this as a serious error, especially for newbies.
(Minor content issue: )In addition, no discussion of 2's complement handling is included. The -12 result is nonsensical without that context.
Note from the Author or Editor:
The reviewer is correct. It is an oversight.
The code should read.
irb(main):001:0> 0b1011
=> 11
irb(main):002:0> ~0b1011 # bitwise not or complement (flip bits)
=> -12
irb(main):003:0> 0b1011 | 0b1010 # bitwise or
=> 11
irb(main):004:0> 0b1011 & 0b1010 # bitwise and
=> 10
irb(main):005:0> 0b1011 ^ 0b1010 # bitwise exclusive or
=> 1
irb(main):006:0* 0b1011 << 1 # shift left
=> 45056
irb(main):007:0> 0b1011 >> 1 # shift right
=> 5
Before the sentence starting "The bitwise operators also . . ." at the bottom of page 84, begin a new paragraph and add this sentence.
"The complement or NOT operator (~) flips the binary bits, that is zeros become ones and ones, zeros. This is how modern computers store negative numbers—in other words, negative numbers are represented by toggling ones and zeros and adding 1 to the bitstream."
|
Baron Schaaf |
Oct 06, 2014 |
|
| Printed |
Page 7
2nd ruby command from the top |
Hi,
When I type in the command ruby -e "puts 'Hello, Matz!'" I get the following error
-bash: !'": event not found
Cheers
Mike
Note from the Author or Editor:
Just invert "/'. Should be:
ruby -e 'puts "Hello, Matz"' |
David Harrison |
Jul 11, 2009 |
|
| Printed |
Page 10
The Tk Toolkit |
After a lot of trying (5 hours, over 2 days) and searching online I cannot get this to work at all. I have followed literally every example out there and I cannot get this to work. How do I get the Tktoolkit to work?
Thanks,
TJ
Note from the Author or Editor:
The section with the heading "The Tk Toolkit" should be removed from page 10 of the book because (1) the example does not work readily; (2) it requires more explanation than is warranted for a first chapter on the subject. |
Anonymous |
Jun 14, 2013 |
|
| Printed |
Page 13
irb 80 % 60 |
Well... 80 percent of 60 is not 20. BUT 80 modulo 60 IS. I am not sure if that is what it is doing... but some clarification would be awesome.
-TJ
Note from the Author or Editor:
I have added a clarifying sentence to the 2nd edition. Instead of:
You can do some simple math:
It now reads:
You can do some simple math, such as addition (_+_), multiplication (_*_), divsion (_/_), subtraction (_-_), and modulo (_%_):
This rewritten sentence could be added to a reprint as well (it is not dependent on Ruby 2.0). |
Anonymous |
Jun 14, 2013 |
|
| Printed |
Page 14
2nd paragrah from the bottom |
"is well-written and as complete it could possibly..."
probably intended to be-- "is well-written and as complete <<as>> it could possibly..."
|
Anonymous |
|
Aug 01, 2007 |
| Printed |
Page 18
Mid-page |
It should be noted the the One-Click Installer does not include the Tcl/Tk library (among others) and you
will have to download them separately. Because of this, I prefer to install Ruby on Windows using
instructions in the next section.
|
Anonymous |
|
|
| Printed |
Page 23
last line of text on page |
http://www.oreilly.com/catalog/learningruby
gives a 404 error
Note from the Author or Editor:
Correct.
The URL should be
http://oreilly.com/catalog/9780596529864/ |
Anonymous |
|
|
| Printed |
Page 27
fourth paragraph |
Here is another form. This block comment conceals several lines from the interpreter with =begin/=end:
The correction should be "Here is another form. This block comment conceals several lines from the
interpreter with =begin/=end (without any leading spaces or tabs:"
This is not a serious problem but an inadvertent space or tab will create an error msg.
Note from the Author or Editor:
Yes, I like this change.
Here is the sentence you should replace it with:
"Here is another form. This block comment conceals several lines from the interpreter with =begin/=end (without any leading spaces or tabs):" |
Anonymous |
|
|
| Printed |
Page 36
Return Values, numeral 3 |
The line says "Now assign method matz to the variables output and puts output"
I believe it should instead read "Now assign method matz to the variable output and puts output" There's only one variable (output) and 'puts output' is a command, not a variable.
Note from the Author or Editor:
This errata is correct. The word "variable" should be singular, not plural. |
Anonymous |
Jan 17, 2010 |
|
| Printed |
Page 48
1st paragraph |
There is an extra "END" on this IF statement while the previous sentence clearly tries to explain
that the keyword "END" is mandatory.
"
In addition, you don't have to use end if you write this code all on one line, like so:
x - 256
if x == 256 then puts "x equals 256" end
"
Note from the Author or Editor:
Change this sentence:
"In addition, you don't have to use end if you write this code all on one line, like so:"
To this:
"In addition, you can write this code all on one line, like so:" |
Anonymous |
|
|
| Printed |
Page 50
1st paragraph |
In reference to an if / else construct, the text reads:
The 'else' keyword gives 'if' an escape hatch. In other words, if the 'if' statement does not evaluate true, the code after 'else'
will be executed, and if 'if' evaluates 'false', the code after 'else' is ignored.
Should probably be something like:
The 'else' keyword gives 'if' an escape hatch. In other words, if the 'if' statement does not evaluate
true, the code after 'else' will be executed, and if 'if' evaluates 'true', (the code after 'if' is
executed and) the code after
'else' is ignored.
Note from the Author or Editor:
Yes. Use the sentence given, except drop the parens. |
Anonymous |
|
|
| Printed |
Page 50, 51
The tighter elsif code on Pg 50 and case code in Pg 51 |
Code on Page 50:
-----------------
lang = :es
if lang == :en: print "dog"
elsif lang == :es: print "perro"
elsif lang == :fr: print "chien"
elsif lang == :de: print "hund"
else puts "no language set; defaut = dog."
end
Code on Page 51:
------------------
ang = :fr
dog = case lang
when :en: "dog"
when :es: "perro"
when :fr: "chien"
when :de: "Hund"
else "dog"
end
These codes will work fine with Ruby 1.8.6 - p287 but will fail using Ruby 1.9.1. To make them work for both version, do not use the colon after the symbols, use the semi-colon or keyword "then" instead as follows:
Code on Page 50:
-----------------
lang = :es
if lang == :en; print "dog"
elsif lang == :es; print "perro"
elsif lang == :fr; print "chien"
elsif lang == :de; print "hund"
else puts "no language set; defaut = dog."
end
Code on Page 51:
------------------
ang = :fr
dog = case lang
when :en; "dog"
when :es; "perro"
when :fr; "chien"
when :de; "Hund"
else "dog"
end
Note from the Author or Editor:
He is correct, and both : and ; will work with 1.8.6, so lets just change the code as he suggests:
Code on Page 50:
-----------------
lang = :es
if lang == :en; print "dog"
elsif lang == :es; print "perro"
elsif lang == :fr; print "chien"
elsif lang == :de; print "hund"
else puts "no language set; defaut = dog."
end
Code on Page 51:
------------------
ang = :fr
dog = case lang
when :en; "dog"
when :es; "perro"
when :fr; "chien"
when :de; "Hund"
else "dog"
end |
Murugappan Ramanathan |
Nov 28, 2009 |
|
| Printed |
Page 51
6th paragra |
code as in book.
lang = :fr
dog = case lang
when :en: "dog"
when :es: print "perro"
when :fr: print "chien"
when :de: print "hund"
else print "dog"
end
Hello,, besides the symbols ending with semi colon for ruby 1.9.1 or later which some one else also mentioned and helped me. You also need to write print to get output to screen
code if you want output
lang = :fr
dog = case lang
when :en; print "dog"
when :es; print "perro"
when :fr; print "chien"
when :de; print "hund"
else print "dog"
end
Note from the Author or Editor:
lang = :fr
dog = case lang
when :en; print "dog"
when :es; print "perro"
when :fr; print "chien"
when :de; print "hund"
else print "dog"
end |
Anonymous |
Oct 09, 2011 |
|
| Printed |
Page 53
At the end of page, example of cash and sum |
This is a logic error of how to use the variable sum. The author did not explain how to use the variable sum. I do not believe the variable sum is used in the calculation.
Note from the Author or Editor:
[Code should read:]
cash = 100_0000.00
cash += 1.00 while cash < 1_000_000.00 # underscores ignored |
Anonymous |
Jun 24, 2009 |
|
| Printed |
Page 65
5th para, 1st bullet |
quote:
hay == nicolay # => false
...
...You could also apply the eql? method and get the same results, though eql? and == are slightly
different:
[bullet] == returns true if two objects are Strings, false otherwise
end quote.
The first bullet is wrong as your own example "hay == nicolay" shows.
See corelib.ruby, which defines == like this:
"Equality?If obj is not a String, returns false. Otherwise, returns true if str <=> obj returns zero."
Also your examples don't show any difference between "==" and ".eql?", since "hay.eql?" also returns
false.
Note from the Author or Editor:
First bullet should say:
? == returns false if right operand is not a string. Otherwise, returns true if str <=> obj returns zero.
"str <=> obj" should be formatted as code. |
Anonymous |
|
|
| Printed |
Page 68
last code sample of section 4.5.4 - The delete method |
This applies to the Safari online version of the book as of May 13, 2008.
The example code doesn't generate the given output:
"That's all folks".delete "abcdefghijklmnopqrstuvwxyz", "^ha" # => "haa"
The .delete method will only delete the lowercase letters, excepting "h" and "a". It will not delete the uppercase letters ("T") or the punctuation (space and single quote), so the result is "Tha' a ", not "haa".
Note from the Author or Editor:
Change line of code to:
"That's all folks".delete "abcdefghijklmnopqrstuvwxyz", "^ha"=> "Tha' a " |
Anonymous |
|
|
| Printed |
Page 74, 75
Code examples |
The code examples using grep do not work in Ruby 1.9.1. The code must be changed to:
ex: pg 74 bottom of page
opening.lines.grep(/men/)
in order to produce the shown output. Similar changes must be made on the examples on pg 75 in order to produce the show output.
Note from the Author or Editor:
Change as specified.
In the intro line, include "(1.9.1)" at the end of the line. |
Anonymous |
Dec 23, 2009 |
|
| Printed |
Page 75
Last three paragraphs |
The author provides this regular expression:
phone.grep(/[\(\d\d\d\)]?\d\d\d-\d\d\d\d/)
This is erroneous and does not work in the way the author explains. In particular, the square brackets around the area code indicate a character class, not a subexpression. Consequently, the supplied regular expression will match strings like '(123-4567' or '1123-4567' or ')123-4567'.
In the last paragraph on the page (and continuing onto page 76) the author states, "The area-code pattern is surrounded by [ and ] so that the ? operator applies to the entire area code.Either form of the phone number, with or without the area code, will work." This is incorrect.
Also, without any anchoring, the supplied expression will match things like '123-123123123123'.
A better expression would have been:
phone.grep( /\b(\(\d\d\d\))?\d\d\d-\d\d\d\d\b/ )
Note from the Author or Editor:
phone.grep(/^(\(\d{3}\))?\d{3}-\d{4}$/) |
Jeremy Madea |
Jul 14, 2012 |
|
| Printed |
Page 82
2nd block of command line examples |
The example "12.quo 5" does not return 2.4, it returns Rational(12, 5)
To obtain that the example should be "12.0.quo 5.0"
|
Anonymous |
|
|
| Printed |
Page 91
Example 5-3 |
This may be an issue since I am using Ruby 2.0.0p195
When I type in list_primes = Prime.new I get the following error-
Prime::new is obsolete. use Prime::instance or class methods of Prime.
Thus I went with list_primes = Prime.instance and all is well!
Not sure if that is the RIGHT way, but it does seem to work...
Note from the Author or Editor:
This error is confirmed and will be corrected in the 2nd edition which will document 2.0.0. But this code is correct for the older version used in the current book. |
Anonymous |
Jun 17, 2013 |
|
| Printed |
Page 96
After 1st paragraph |
irb(main):008:0> digits = Array(0..9)
=> [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
not [1, 2, 3, 4, 5, 6, 7, 8, 9]
|
Anonymous |
|
|
| Printed |
Page 99
2nd-last paragraph |
Under the code starting 'last_part = q3.concat(q4)', the book claims 'concat always returns a new array; it does not add elements to an existing array the way << does'. This seems incorrect; the elements are actually added to the original array, e.g.
myarray=[1,2]; myarray.concat([3,4]); puts myarray.join(",")' #gives 1,2,3,4
Note from the Author or Editor:
I have deleted the assertion in the source (on Atlas). The next time the book is printed, it will no longer be in the text. |
Tung Jin Chew |
Nov 10, 2012 |
|
| Printed |
Page 102
5th code block |
I believe in the fifth code block on the page (the one right above the heading
|
Anonymous |
Aug 07, 2008 |
|
| Printed |
Page 102
5th code block |
I believe in the fifth code block on the page (the one right above the heading "As a String", the elements "May", "June", and "July" should be in bold, not "June", "July", and "August".
|
Anonymous |
|
|
| Printed |
Page 119
middle of page |
"run the program with these three files on the command line:"
# argf.rb sonnet_29.txt sonnet_119.txt sonnet_129.txt
should be
ruby argf.rb sonnet_29.txt sonnet_119.txt sonnet_129.txt
|
Anonymous |
|
|
| Printed |
Page 123
2nd paragraph |
There are two mistakes in the 2nd paragraph. Original text is
Note from the Author or Editor:
Please make the following correction to the 2nd and 3rd sentences in the 2nd paragraph on page 123.
"The first argument is 1, which is the numeric file descriptor for standard output. Standard output can also be represented by the predefined Ruby variable $stdout [...] |
Anonymous |
Jul 01, 2009 |
|
| Printed |
Page 215
Chapter 4 review question 9 |
to_a was the intended answer but split(//) will work too.
Here is the difference:
irb(main):001:0> "hello there".split(//)
=> ["h", "e", "l", "l", "o", " ", "t", "h", "e", "r", "e"]
irb(main):002:0> "hello there".to_a
=> ["hello there"]
|
Anonymous |
|
|