Nuby question - printing substring as non-ASCII

ruby-talk
1

I'm reading in a string of numbers, as follows:

" 1 45.3456 "

How do I write out the first non-whitespace element as a number? Ruby
wants to express as it in ASCII, and the .to_i method doesn't seem to
work on a substring.

Thanks in advance.

TPL

···

--
Posted via http://www.ruby-forum.com/.

2

Thomas Luedeke wrote:

I'm reading in a string of numbers, as follows:

" 1 45.3456 "

How do I write out the first non-whitespace element as a number? Ruby
wants to express as it in ASCII, and the .to_i method doesn't seem to
work on a substring.

Doesn't seem to? Code please.

Also, the following works for me:

  irb(main):009:0> " 1 45.3456 ".strip.split(/\s+/).map { |i|
                     i.to_i
                   }
  => [1, 45]

(Of course, to_i coerces to integers, so the body of the map block would
have to be more complicated to get floats too.)

David Vallner

3

Thomas Luedeke wrote:

I'm reading in a string of numbers, as follows:

" 1 45.3456 "

How do I write out the first non-whitespace element as a number? Ruby
wants to express as it in ASCII, and the .to_i method doesn't seem to
work on a substring.

Thanks in advance.

TPL

--
Posted via http://www.ruby-forum.com/\.

irb(main):001:0> " 1 45.3456 ".strip.to_i()
=> 1

4

Then why not call to_i on a whole string?

" 1 45.3456 ".to_i
" 1 45.3456 ".to_f

It will find the first number and convert it to Fixnum or Float.

Dmitry

Thomas Luedeke wrote:

···

I'm reading in a string of numbers, as follows:

" 1 45.3456 "

How do I write out the first non-whitespace element as a number? Ruby
wants to express as it in ASCII, and the .to_i method doesn't seem to
work on a substring.

Thanks in advance.

TPL

--
Posted via http://www.ruby-forum.com/\.

5

Thomas Luedeke wrote:

I'm reading in a string of numbers, as follows:

" 1 45.3456 "

How do I write out the first non-whitespace element as a number? Ruby
wants to express as it in ASCII, and the .to_i method doesn't seem to
work on a substring.

Thanks in advance.

TPL

Thanks. Dumb question, but I'm kinda deep in the throes of the "suck"
stage of learning Ruby. The following also seems to work (at least for
the purposes of reading in and writing formatted output):

irb(main):001:0> string=" 1 45.3456 "
=> " 1 45.3456 "

irb(main):003:0> string.strip
=> "1 45.3456"

irb(main):004:0> string.split[1]
=> "45.3456"

irb(main):005:0> string.split[0]
=> "1"

···

--
Posted via http://www.ruby-forum.com/\.

6

Dmitry Buzdin wrote:

Then why not call to_i on a whole string?

" 1 45.3456 ".to_i
" 1 45.3456 ".to_f

It will find the first number and convert it to Fixnum or Float.

Dmitry

You're absolutely right, Dmitry... .strip() is not necessary. But I
tend to be a bit anal-retentive about such things :o|

7

Here is one way:
irb(main):001:0> string = " 1 45.3456 "
=> " 1 45.3456 "
irb(main):002:0> substrings = string.scan /[^\s]+/
=> ["1", "45.3456"]
irb(main):003:0> substrings.first.to_i
=> 1

The second line of code is saying: Scan the string, and return an
Array of strings that were made up of one or more non-whitespace
characters.

substrings.first is the same as substrings[0]

···

On 11/17/06, Thomas Luedeke <tluedeke@excite.com> wrote:

Thomas Luedeke wrote:
> I'm reading in a string of numbers, as follows:
>
> " 1 45.3456 "
>
> How do I write out the first non-whitespace element as a number? Ruby
> wants to express as it in ASCII, and the .to_i method doesn't seem to
> work on a substring.
>
> Thanks in advance.
>
> TPL

Thanks. Dumb question, but I'm kinda deep in the throes of the "suck"
stage of learning Ruby. The following also seems to work (at least for
the purposes of reading in and writing formatted output):

irb(main):001:0> string=" 1 45.3456 "
=> " 1 45.3456 "

irb(main):003:0> string.strip
=> "1 45.3456"

irb(main):004:0> string.split[1]
=> "45.3456"

irb(main):005:0> string.split[0]
=> "1"

8

no need to strip
" 1 45.3456".to_i => 1

···

----- Original Message ----- From: "Patrick Spence" <djmj12@gmail.com>
To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
Sent: Friday, November 17, 2006 9:45 AM
Subject: Re: Nuby question - printing substring as non-ASCII

Thomas Luedeke wrote:

I'm reading in a string of numbers, as follows:

" 1 45.3456 "

How do I write out the first non-whitespace element as a number? Ruby
wants to express as it in ASCII, and the .to_i method doesn't seem to
work on a substring.

Thanks in advance.

TPL

--
Posted via http://www.ruby-forum.com/\.

irb(main):001:0> " 1 45.3456 ".strip.to_i()
=> 1

9

Hi --

Thomas Luedeke wrote:
> I'm reading in a string of numbers, as follows:
>
> " 1 45.3456 "
>
> How do I write out the first non-whitespace element as a number? Ruby
> wants to express as it in ASCII, and the .to_i method doesn't seem to
> work on a substring.
>
> Thanks in advance.
>
> TPL

Thanks. Dumb question, but I'm kinda deep in the throes of the "suck"
stage of learning Ruby. The following also seems to work (at least for
the purposes of reading in and writing formatted output):

irb(main):001:0> string=" 1 45.3456 "
=> " 1 45.3456 "

irb(main):003:0> string.strip
=> "1 45.3456"

irb(main):004:0> string.split[1]
=> "45.3456"

irb(main):005:0> string.split[0]
=> "1"

Here is one way:
irb(main):001:0> string = " 1 45.3456 "
=> " 1 45.3456 "
irb(main):002:0> substrings = string.scan /[^\s]+/
=> ["1", "45.3456"]
irb(main):003:0> substrings.first.to_i
=> 1

The second line of code is saying: Scan the string, and return an
Array of strings that were made up of one or more non-whitespace
characters.

substrings.first is the same as substrings[0]

Another possibility:

irb(main):001:0> require 'scanf'
=> true
irb(main):002:0> string = " 1 45.3456 "
=> " 1 45.3456 "
irb(main):003:0> string.scanf("%d")
=> [1]

You have to get it out of the array, but you don't have to convert it
(it's already an integer).

David

···

On Sat, 18 Nov 2006, Wilson Bilkovich wrote:

On 11/17/06, Thomas Luedeke <tluedeke@excite.com> wrote:

--
                   David A. Black | dblack@rubypal.com
Author of "Ruby for Rails" [1] | Ruby/Rails training & consultancy [3]
DABlog (DAB's Weblog) [2] | Co-director, Ruby Central, Inc. [4]
[1] Ruby for Rails | [3] http://www.rubypowerandlight.com
[2] http://dablog.rubypal.com | [4] http://www.rubycentral.org