Fized size record from a string


#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.


#3

On Mar 10, 8:51 am, lucac81 removed_email_address@domain.invalid wrote:

Thank you very much
Simple, not very intelligent way could be

(‘string’ + ‘-’*30)[0…16]


#4

On Mar 10, 2:51 pm, lucac81 removed_email_address@domain.invalid wrote:

Thank you very much
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)


#5

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

Thank you very much

irb> str = “too short”
=> “too short”
irb> lng = “this one is big enough”
=> “this one is big enough”

With Kernel#sprintf (which String#% calls)
irb> “%-16.16s”%str
=> "too short "
irb> “%-16.16s”%lng
=> "this one is big "

With String#ljust
irb> str.ljust(16)
=> "too short "
irb> lng.ljust(16)
=> “this one is big enough”

With String#[] (not what you want for short ones)
irb> str[0,16]
=> “too short”
irb> lng[0,16]
=> "this one is big "

-Rob

Rob B. http://agileconsultingllc.com
removed_email_address@domain.invalid