Asp Forum - Placing tabs in strings in irb

Michael W. Ryder

1/23/2007 12:44:00 AM

Is there any reason I cannot embed tabs in a string while using irb? I
am trying to create a string using tabs to separate the various values
for testing -- i.e. a = '1 2 3 4'. Using irb it either ignores the tab
character or places a random value in the string.
On a related note why is the value for the above string '1' if I use
a.to_i to display it? I would have expected an error.

14 Answers

MikeGee

1/23/2007 12:48:00 AM

Lincoln Anderson

1/23/2007 1:06:00 AM

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MikeGee wrote:
> Michael W. Ryder wrote:
>> Is there any reason I cannot embed tabs in a string while using irb? I
>> am trying to create a string using tabs to separate the various values
>> for testing -- i.e. a = '1 2 3 4'. Using irb it either ignores the tab
>> character or places a random value in the string.
>> On a related note why is the value for the above string '1' if I use
>> a.to_i to display it? I would have expected an error.
>
>
> a = "1\t2\t3\t4"
>
>
>

Actually, I tried this and it gives a string literal back

=>"1\t2\t3\t4"

This occurs as well if inserted into a full ruby script (not just irb).

Lincoln Anderson
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WoNáDo

1/23/2007 1:19:00 AM

Lincoln Anderson schrieb:
> Actually, I tried this and it gives a string literal back
>
> =>"1\t2\t3\t4"

It works fine. "irb"'s output is after applying "inspect".

irb(main):001:0> a = "1\t2"
=> "1\t2"
irb(main):002:0> puts a
1 2
=> nil
irb(main):003:0> a.length
=> 3

Wolfgang Nádasi-Donner

Tim Hunter

1/23/2007 1:22:00 AM

Lincoln Anderson wrote:
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>
> MikeGee wrote:
>
>> Michael W. Ryder wrote:
>>
>>> Is there any reason I cannot embed tabs in a string while using irb? I
>>> am trying to create a string using tabs to separate the various values
>>> for testing -- i.e. a = '1 2 3 4'. Using irb it either ignores the tab
>>> character or places a random value in the string.
>>> On a related note why is the value for the above string '1' if I use
>>> a.to_i to display it? I would have expected an error.
>>>
>> a = "1\t2\t3\t4"
>>
>>
>>
>>
>
> Actually, I tried this and it gives a string literal back
>
> =>"1\t2\t3\t4"
>
> This occurs as well if inserted into a full ruby script (not just irb).
>

Remember irb uses Kernel#p to echo the expression values. Try

a = "1\t2\t3\t4"
puts a

Also, String#to_ is working as designed. The ri documentation is quite
explicit.

$ ri String.to_i
------------------------------------------------------------ String#to_i
str.to_i(base=10) => integer
------------------------------------------------------------------------
Returns the result of interpreting leading characters in str as an
integer base base (2, 8, 10, or 16). Extraneous characters past
the end of a valid number are ignored. If there is not a valid
number at the start of str, 0 is returned. This method never
raises an exception.

"12345".to_i #=> 12345
"99 red balloons".to_i #=> 99

Joel VanderWerf

1/23/2007 1:25:00 AM

Michael W. Ryder wrote:
> Is there any reason I cannot embed tabs in a string while using irb? I
> am trying to create a string using tabs to separate the various values
> for testing -- i.e. a = '1 2 3 4'. Using irb it either
> ignores the tab character or places a random value in the string.
> On a related note why is the value for the above string '1' if I use
> a.to_i to display it? I would have expected an error.

If you *want* this to error, use

irb(main):001:0> Integer("1 2")
ArgumentError: invalid value for Integer: "1 2"
from (irb):4:in `Integer'
from (irb):4

--
vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407

Lincoln Anderson

1/23/2007 1:26:00 AM

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Nathan Smith wrote:
>>
>> Actually, I tried this and it gives a string literal back
>>
>> =>"1\t2\t3\t4"
>>
>> This occurs as well if inserted into a full ruby script (not just irb).
>>
>> Lincoln Anderson
>
>
> In irb if you do a="1\t2\t3\t4" it replies with "1\t2\t3\t4". But, if
> you do
> puts a, it gives you: 1 2 3 4.
>
> The string must be in double quotes for this to work.
>
>> On a related note why is the value for the above string '1' if I use
>> a.to_i to display it? I would have expected an error.
>
> Extraneous characters past the end of a valid number are ignored, according
> to the docs.
>
> Nate
>

Okay, shoulda guessed that the "output" from defining a wouldn't be
formatted. And when I check my ruby script I see that I had it single
quoted, not double-quoted. Cool, I learneded something today.

Lincoln Anderson
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Michael W. Ryder

1/23/2007 1:54:00 AM

Joel VanderWerf wrote:
> Michael W. Ryder wrote:
>> Is there any reason I cannot embed tabs in a string while using irb?
>> I am trying to create a string using tabs to separate the various
>> values for testing -- i.e. a = '1 2 3 4'. Using irb it
>> either ignores the tab character or places a random value in the string.
>> On a related note why is the value for the above string '1' if I use
>> a.to_i to display it? I would have expected an error.
>
> If you *want* this to error, use
>
> irb(main):001:0> Integer("1 2")
> ArgumentError: invalid value for Integer: "1 2"
> from (irb):4:in `Integer'
> from (irb):4
>
Thanks for the tip. I had known about the to_i method and assumed that
was the only way to do the conversion.

George

1/23/2007 1:58:00 AM

On 1/23/07, Michael W. Ryder <_mwryder@worldnet.att.net> wrote:
> Is there any reason I cannot embed tabs in a string while using irb? I
> am trying to create a string using tabs to separate the various values
> for testing -- i.e. a = '1 2 3 4'. Using irb it either ignores the tab
> character or places a random value in the string.
> On a related note why is the value for the above string '1' if I use
> a.to_i to display it? I would have expected an error.

I'm guessing this behavior is due to readline, which is normally
compiled into into irb if available. If so, you can also insert tabs
using M-TAB (a.k.a. alt-tab). Try "info readline" for more info (or
google "info readline" if you don't have it available).

Michael W. Ryder

1/23/2007 2:06:00 AM

MikeGee wrote:
> Michael W. Ryder wrote:
>> Is there any reason I cannot embed tabs in a string while using irb? I
>> am trying to create a string using tabs to separate the various values
>> for testing -- i.e. a = '1 2 3 4'. Using irb it either ignores the tab
>> character or places a random value in the string.
>> On a related note why is the value for the above string '1' if I use
>> a.to_i to display it? I would have expected an error.
>
>
> a = "1\t2\t3\t4"
>

Thank you for the tip. It is going to be hard to remember which string
representation to use for what purpose but I guess that is part of
learning the language.

Michael W. Ryder

1/23/2007 2:14:00 AM

George Ogata wrote:
> On 1/23/07, Michael W. Ryder <_mwryder@worldnet.att.net> wrote:
>> Is there any reason I cannot embed tabs in a string while using irb? I
>> am trying to create a string using tabs to separate the various values
>> for testing -- i.e. a = '1 2 3 4'. Using irb it
>> either ignores the tab
>> character or places a random value in the string.
>> On a related note why is the value for the above string '1' if I use
>> a.to_i to display it? I would have expected an error.
>
> I'm guessing this behavior is due to readline, which is normally
> compiled into into irb if available. If so, you can also insert tabs
> using M-TAB (a.k.a. alt-tab). Try "info readline" for more info (or
> google "info readline" if you don't have it available).
>

Using alt-tab on my XP Pro computer results in another window popping up
and does not insert a tab character into the string. I will just have
to remember to use double quotes and \t for tabs.

comp.lang.ruby

Placing tabs in strings in irb

Michael W. Ryder

MikeGee

Lincoln Anderson

WoNáDo

Tim Hunter

Joel VanderWerf

Lincoln Anderson

Michael W. Ryder

George

Michael W. Ryder

Michael W. Ryder

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