Fized size record from a string

ruby-talk
1

Hello, I'm new to Ruby, and I'm learning it with a project that also
involves rails...
I'm stuck with an apparently simple problem, I receive from a form a
String and I need to extend it to a fixed char number (it must be 16
chars with eventual trailing spaces)
I've tought to convert it to an array, it's easy but I don't know how
to extend it to the needed size.
Also I could add spaces to the string, but the again how can i control
how many I need to add?
Any hint on how I could do that?
Thank you very much

2

lucac81 wrote:

Hello, I'm new to Ruby, and I'm learning it with a project that also
involves rails...
I'm stuck with an apparently simple problem, I receive from a form a
String and I need to extend it to a fixed char number (it must be 16
chars with eventual trailing spaces)

Look at the String#% method:

irb(main):003:0> "%-16s" % "123"
=> "123 "

This won't work if the original string is longer than 16, though. In
that case you just a copy of the original string.

···

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Posted via http://www.ruby-forum.com/\.

3

Simple, not very intelligent way could be

('string' + '-'*30)[0..16]

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On Mar 10, 8:51 am, lucac81 <lcors...@gmail.com> wrote:

Hello, I'm new to Ruby, and I'm learning it with a project that also
involves rails...
I'm stuck with an apparently simple problem, I receive from a form a
String and I need to extend it to a fixed char number (it must be 16
chars with eventual trailing spaces)
I've tought to convert it to an array, it's easy but I don't know how
to extend it to the needed size.
Also I could add spaces to the string, but the again how can i control
how many I need to add?
Any hint on how I could do that?
Thank you very much

4

Uhmm I just found how to achieve this... using the ljust method of the
String class...

  str.ljust(integer, padstr=' ') => new_str

If integer is greater than the length of str, returns a new String of
length integer with str left justified and padded with padstr;
otherwise, returns str.

   "hello".ljust(4) #=> "hello"
   "hello".ljust(20) #=> "hello "
   "hello".ljust(20, '1234') #=> "hello123412341234123"

this solves my problem, and there is the rjust method that works fine
on the other side (I need that too)

···

On Mar 10, 2:51 pm, lucac81 <lcors...@gmail.com> wrote:

Hello, I'm new to Ruby, and I'm learning it with a project that also
involves rails...
I'm stuck with an apparently simple problem, I receive from a form a
String and I need to extend it to a fixed char number (it must be 16
chars with eventual trailing spaces)
I've tought to convert it to an array, it's easy but I don't know how
to extend it to the needed size.
Also I could add spaces to the string, but the again how can i control
how many I need to add?
Any hint on how I could do that?
Thank you very much

5

Hello, I'm new to Ruby, and I'm learning it with a project that also
involves rails...
I'm stuck with an apparently simple problem, I receive from a form a
String and I need to extend it to a fixed char number (it must be 16
chars with eventual trailing spaces)
I've tought to convert it to an array, it's easy but I don't know how
to extend it to the needed size.
Also I could add spaces to the string, but the again how can i control
how many I need to add?
Any hint on how I could do that?
Thank you very much

str = "too short"

=> "too short"

lng = "this one is big enough"

=> "this one is big enough"

With Kernel#sprintf (which String#% calls)

"%-16.16s"%str

=> "too short "

"%-16.16s"%lng

=> "this one is big "

With String#ljust

str.ljust(16)

=> "too short "

lng.ljust(16)

=> "this one is big enough"

With String# (not what you want for short ones)

str[0,16]

=> "too short"

lng[0,16]

=> "this one is big "

-Rob

Rob Biedenharn http://agileconsultingllc.com
Rob@AgileConsultingLLC.com

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On Mar 10, 2009, at 9:53 AM, lucac81 wrote: