From: Holden Glova <dsafari@...>
Date: 2001-12-26T13:43:17+09:00
Subject: [ruby-talk:29432] Re: Help with Regular Expression

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On Wed, 26 Dec 2001 17:11, Vincent Foley wrote:
> Hi,
>
> I would like to know how I would check if a variable's content
> matches a regular expression.  Example (complete the code):
>
> [code]
> #!/usr/bin/env ruby
>
> a = gets.chomp
>
> # Complete here.  I want to know if a is an integer with regular
> # expressions (/\d*/).  Can I do that? How?
>
> [/code]

Hi Vincent,

You could try something along the lines of this:

irb(main):010:0> a = "+232"
"+232"
irb(main):011:0> a =~ /^[+-]?\d+$/
0
irb(main):012:0> a = "-232"
"-232"
irb(main):013:0> a =~ /^[+-]?\d+$/
0
irb(main):016:0> a = "99999"
"99999"
irb(main):017:0> a =~ /^[+-]?\d+$/
0
irb(main):014:0> a = "sldkfjer"
"sldkfjer"
irb(main):015:0> a =~ /^[+-]?\d+$/
nil

Or, if you are not entirely fixed on using regular expressions you 
could also do this. You would do your Integer validation within a 
block that rescues the ArguementError exception. I prefer this one 
for integer validation because to me it is clearer. Thanks to matju 
in #ruby-talk for showing me this yesterday.

irb(main):006:0> a = "99999"
"99999"
irb(main):007:0> Integer(a)
99999
irb(main):002:0> a = "+2343423"
"+2343423"
irb(main):003:0> Integer(a)
2343423
irb(main):004:0> a = "blarg"
"blarg"
irb(main):005:0> Integer(a)
ArgumentError: invalid value for Integer: "blarg"
        from (irb):5:in `Integer'
        from (irb):5

Hope that helps. Have fun.

- -- 
Signed,
Holden Glova
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