How to format string in Ruby using printf/sprintf

Question

I want to create a table:

Iterations                      Value
         1                      123  
         2                      124
        ..                      
       100                      124212
       101                      1242142

If I'm able to do so, do you know which website for reference is good for Ruby?

Answer 1

Already asked here: Is there a Ruby equivalent to the C++ std::setw(int) function?

puts "%10s" % ["foo"]  # => "       foo"
puts "%-10s" % ["bar"] # => "foo       "

Answer 2

You can use rjust or ljust.

"123".rjust(10, '0')
#=> "0000000123"
"123".ljust(10, '0')
#=> "1230000000"