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Ruby Programming Language
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How to check if a string is a integer ?
How to check if a string is a integer ?
After seached in google, I can't find any information. All ISINTEGER
function is about Javascript.
Thank you.
--
WenGe Wang
w wg wrote: > How to check if a string is a integer ? > After seached in google, I can't find any information. All ISINTEGER
> function is about Javascript.
> Thank you.
In case Integer() confuses you: that's Kernel#Integer(), a method, not
the class Integer.
Also you can use a regex, e.g. str =~ /\A[+-]?\d+\z/
Regards
Stefan
--
Posted via http://www.ruby-forum.com/.
On 04/06/07, w wg <duzu@gmail.com> wrote:
> How to check if a string is a integer ?
You can use either the String#to_i or Kernel#Integer methods
irb(main):001:0> "1234".to_i
=> 1234
irb(main):002:0> "123A".to_i
=> 123
irb(main):003:0> "A123".to_i
=> 0
irb(main):004:0> Integer("A1234")
ArgumentError: invalid value for Integer: "A1234"
from (irb):4:in `Integer'
from (irb):4
irb(main):005:0> Integer("1234A")
ArgumentError: invalid value for Integer: "1234A"
from (irb):5:in `Integer'
from (irb):5
irb(main):006:0> Integer("1234")
=> 1234
irb(main):007:0>
Farrel
w wg wrote: > How to check if a string is a integer ? > After seached in google, I can't find any information. All ISINTEGER
> function is about Javascript.
> Thank you.
123.is_a? Integer
=> true
'David'.is_a? Integer
=> false
David
http://rubyonwindows.blogspot.com
--
Posted via http://www.ruby-forum.com/.
Thank you, it works.
How did you find the Integer method of class Kernel ?
I typed "ri Kernel", but I can't find any Kernel's class method.
2007/6/4, Farrel Lifson <farrel.lif@gmail.com>:
> On 04/06/07, w wg <duzu @gmail.com> wrote: > > How to check if a string is a integer ? > You can use either the String#to_i or Kernel#Integer methods
> irb(main):001:0> "1234".to_i
> => 1234
> irb(main):002:0> "123A".to_i
> => 123
> irb(main):003:0> "A123".to_i
> => 0
> irb(main):004:0> Integer("A1234")
> ArgumentError: invalid value for Integer: "A1234"
> from (irb):4:in `Integer'
> from (irb):4
> irb(main):005:0> Integer("1234A")
> ArgumentError: invalid value for Integer: "1234A"
> from (irb):5:in `Integer'
> from (irb):5
> irb(main):006:0> Integer("1234")
> => 1234
> irb(main):007:0>
> Farrel
--
WenGe Wang
On 04/06/07, David Mullet <david.mul@gmail.com> wrote:
> w wg wrote:
> 123.is_a? Integer
> => true
> 'David'.is_a? Integer
> => false
That won't work
irb(main):001:0> "123".is_a? Integer
=> false
Farrel
Hi,
Am Montag, 04. Jun 2007, 22:46:45 +0900 schrieb Stefan Rusterholz:
> w wg wrote: > > How to check if a string is a integer ? > Also you can use a regex, e.g. str =~ /\A[+-]?\d+\z/
well. Something like:
class String
def as_uint
case self
when /\A0x[0-9a-f]+\z/i then hex
when /\A0b[0-1]+\z/ then bin
when /\A0[0-7]+\z/ then oct
when /\A(?:0|[1-9]\d*)\z/ then to_i
end
end
end
There should be a combination of Kernel#eval and $SAFE, too.
Bertram
--
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de
Farrel Lifson wrote: > On 04/06/07, David Mullet <david.mul @gmail.com> wrote: >> w wg wrote: >> 123.is_a? Integer >> => true >> 'David'.is_a? Integer >> => false > That won't work
> irb(main):001:0> "123".is_a? Integer
> => false
> Farrel
Perhaps I shouldn't post before my first cup of tea.
David
--
Posted via http://www.ruby-forum.com/.
Bertram Scharpf wrote: > Hi, > Am Montag, 04. Jun 2007, 22:46:45 +0900 schrieb Stefan Rusterholz:
>> w wg wrote:
>> > How to check if a string is a integer ?
>> Also you can use a regex, e.g. str =~ /\A[+-]?\d+\z/
> In many cases it's useful to test for hex representations as
> well. Something like:
representations of Integers ruby itself understands. It is probably much
faster than a case/when, you also will have the value converted to an
integer afterwards, which you most probably want anyway.
Regards
Stefan
--
Posted via http://www.ruby-forum.com/.
Hi,
Am Dienstag, 05. Jun 2007, 01:00:10 +0900 schrieb Stefan Rusterholz:
> Bertram Scharpf wrote: > > Am Montag, 04. Jun 2007, 22:46:45 +0900 schrieb Stefan Rusterholz: > >> w wg wrote: > >> > How to check if a string is a integer ? > >> Also you can use a regex, e.g. str =~ /\A[+-]?\d+\z/
> > In many cases it's useful to test for hex representations as
> > well. Something like:
> In those cases I'd even more use Integer(). It accepts about all
> representations of Integers ruby itself understands.
Bertram
--
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de
From: w wg [mailto:duzu@gmail.com] :
# I typed "ri Kernel", but I can't find any Kernel's class method.
C:\family\ruby>qri integer
--------------------------------------------------------- Kernel#Integer
Integer(arg) => integer
------------------------------------------------------------------------
Converts _arg_ to a +Fixnum+ or +Bignum+. Numeric types are
converted directly (with floating point numbers being truncated).
If _arg_ is a +String+, leading radix indicators (+0+, +0b+, and
+0x+) are honored. Others are converted using +to_int+ and +to_i+.
This behavior is different from that of +String#to_i+.
Integer(123.999) #=> 123
Integer("0x1a") #=> 26
Integer(Time.new) #=> 1049896590
same w qri kernel#integer
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