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.
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.
You can use Integer(), it raises if the String passed is not an integer.
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
On 04/06/07, w wg [email protected] 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.
Call the is_a? (or kind_of?) method on the object:
123.is_a? Integer
=> true
‘David’.is_a? Integer
=> false
David
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 L. [email protected]:
On 04/06/07, David M. [email protected] 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 R.:
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:
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 S. wrote:
Hi,
Am Montag, 04. Jun 2007, 22:46:45 +0900 schrieb Stefan R.:
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. 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
Farrel L. wrote:
On 04/06/07, David M. [email protected] wrote:
w wg wrote:
123.is_a? Integer
=> true
‘David’.is_a? Integer
=> falseThat won’t work
irb(main):001:0> “123”.is_a? Integer
=> falseFarrel
Of course not. Duh! My apologies.
Perhaps I shouldn’t post before my first cup of tea.
David
From: w wg [mailto:[email protected]] :
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
Hi,
Am Dienstag, 05. Jun 2007, 01:00:10 +0900 schrieb Stefan R.:
In those cases I’d even more use Integer(). It accepts about all
representations of Integers ruby itself understands.
Aah! I did not know that. Cool. Thanks.
Bertram