How to pad a string with spaces in Ruby?

Question

Is there a Ruby function that can pad a string?

Original [477, 4770]

Expected ["477 ", "4770 "]

Can you provide an example code otherwise it's not really clear what you want? — Ionic
– Ionic, Commented Jun 23, 2015 at 7:25

Nikita Fedyashev · Accepted Answer · 2022-10-07 14:57:08Z

30

You should use String#ljust from Ruby standard library:

arr = [477, 4770]
strings = arr.map { |number| number.to_s.ljust(5) }
# => ["477  ", "4770 "]

edited Oct 7, 2022 at 14:57

Nikita Fedyashev

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answered Jun 23, 2015 at 7:28

Paweł Dawczak

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1 Comment

stwr667 Over a year ago

Obviously use rjust(5) to add padding spaces to the left side of the string (at the risk of stating the obvious!) - apidock.com/ruby/String/rjust

Ivaylo Strandjev · Accepted Answer · 2015-06-23 07:28:12Z

13

You need the method String#ljust. Here is an example:

t = 123
s = t.to_s.ljust(5, ' ')

Please note that ' ' is the default padding symbol. I only added it for clarity.

answered Jun 23, 2015 at 7:28

Ivaylo Strandjev

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Comments

floum · Accepted Answer · 2015-06-23 08:20:04Z

2

You can use printf formatting from Kernel as well :

arr = [477, 4770]
arr.map { |i| "%-5d" % i }

answered Jun 23, 2015 at 8:20

floum

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Comments

Thomas Ruiz · Accepted Answer · 2015-06-23 08:26:33Z

2

arr = [477, 4770]

arr.collect {|num| num.to_s.ljust(5)}

edited Jun 23, 2015 at 8:26

Thomas Ruiz

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answered Jun 23, 2015 at 7:29

Amit Thawait

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