How to determine if a string is printable?

ruby-talk
1

Is there an easy way to test if a string is printable (doesn't contain
control characters)? Something easier than listing out all the letters,
numbers, and punctuation and checking each character.

Mike Steiner

2

if(string =~ /.*[\a\b\e\f\n\r\t\v].*/)
  puts "Invalid string"
else
  puts string + " is ok"
end

···

On 5/15/07, Mike Steiner <mikejaysteiner@gmail.com> wrote:

Is there an easy way to test if a string is printable (doesn't contain
control characters)? Something easier than listing out all the letters,
numbers, and punctuation and checking each character.

Mike Steiner

3

Is there an easy way to test if a string is printable (doesn't contain
control characters)? Something easier than listing out all the letters,
numbers, and punctuation and checking each character.

Based on: http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/248540

To test for non-printable characters, use:

  str =~ /[^[:print:]]/

Regards,

Bill

···

From: "Mike Steiner" <mikejaysteiner@gmail.com>

4

Bill Kelly wrote:

From: "Mike Steiner" <mikejaysteiner@gmail.com>

Is there an easy way to test if a string is printable (doesn't contain
control characters)? Something easier than listing out all the letters,
numbers, and punctuation and checking each character.

Based on: http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/248540

To test for non-printable characters, use:

str =~ /[^[:print:]]/

Even though I am not the OP I tried that and using index but none of them seem to work. I get an error message saying "warning character class has '[' without escape" followed by "warning regexp has ']' without escape" and the return is nil regardless what is in the string.
Is there something I am missing here?

···

Regards,

Bill

5

Bill Kelly wrote:

Based on: http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/248540

To test for non-printable characters, use:

str =~ /[^[:print:]]/

Even though I am not the OP I tried that and using index but none of them seem to work. I get an error message saying "warning character class has '[' without escape" followed by "warning regexp has ']' without escape" and the return is nil regardless what is in the string.
Is there something I am missing here?

Not sure. It works for me, without warnings even with ruby -w on:
ruby 1.8.4 (2005-12-24) [i386-mswin32]

And in IRB:

irb(main):117:0> "abc\ndef" =~ /[^[:print:]]/
=> 3 # yes, a non-printable character was found at idx 3

irb(main):118:0> "abcdef" =~ /[^[:print:]]/
=> nil # no, a non-printable character was not found

Regards,

Bill

···

From: "Michael W. Ryder" <_mwryder@worldnet.att.net>

6

Bill Kelly wrote:

From: "Michael W. Ryder" <_mwryder@worldnet.att.net>

Bill Kelly wrote:

Based on: http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/248540

To test for non-printable characters, use:

str =~ /[^[:print:]]/

Even though I am not the OP I tried that and using index but none of them seem to work. I get an error message saying "warning character class has '[' without escape" followed by "warning regexp has ']' without escape" and the return is nil regardless what is in the string.
Is there something I am missing here?

Not sure. It works for me, without warnings even with ruby -w on:
ruby 1.8.4 (2005-12-24) [i386-mswin32]

And in IRB:

irb(main):117:0> "abc\ndef" =~ /[^[:print:]]/
=> 3 # yes, a non-printable character was found at idx 3

irb(main):118:0> "abcdef" =~ /[^[:print:]]/
=> nil # no, a non-printable character was not found

OK, I see what I did. I forgot the trailing colon. Still getting used to the language and regular expressions.

···

Regards,

Bill

7

probably not exactly what you're looking for but I use this quite often for
white space removal:
" a".strip.empty?

···

On 5/16/07, Michael W. Ryder <_mwryder@worldnet.att.net> wrote:

Bill Kelly wrote:
> From: "Michael W. Ryder" <_mwryder@worldnet.att.net>
>> Bill Kelly wrote:
>>>
>>> Based on:
>>> http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/248540
>>>
>>> To test for non-printable characters, use:
>>>
>>> str =~ /[^[:print:]]/
>>>
>> Even though I am not the OP I tried that and using index but none of
>> them seem to work. I get an error message saying "warning character
>> class has '[' without escape" followed by "warning regexp has ']'
>> without escape" and the return is nil regardless what is in the string.
>> Is there something I am missing here?
>
> Not sure. It works for me, without warnings even with ruby -w on:
> ruby 1.8.4 (2005-12-24) [i386-mswin32]
>
> And in IRB:
>
> irb(main):117:0> "abc\ndef" =~ /[^[:print:]]/
> => 3 # yes, a non-printable character was found at idx 3
>
> irb(main):118:0> "abcdef" =~ /[^[:print:]]/
> => nil # no, a non-printable character was not found
>

OK, I see what I did. I forgot the trailing colon. Still getting used
to the language and regular expressions.

> Regards,
>
> Bill
>

8

Regular expression syntax is probably best thought of as a language of
it's own. Or perhaps a family of languages since there are so many
dialects.

···

On 5/16/07, Michael W. Ryder <_mwryder@worldnet.att.net> wrote:

OK, I see what I did. I forgot the trailing colon. Still getting used
to the language and regular expressions.

--
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/