CODEWITHSUNDEEP
ruby-on-railsruby
sjsc
sjsc

Reputation: 4632

Ruby on Rails: How do you add add zeros in front of a number if it's under 10?

I'm looking to convert single digit numbers to two-digit numbers like so:

9 ==> 09
5 ==> 05
12 == 12
4 ==> 04

I figure I could put a bunch of if-else statements (if number is under 10, then do a gsub) but figure that's horrible coding. I know Rails has number_with_precision but I see that it only applies to decimal numbers. Any ideas on how to convert single-digits to two-digits?

Upvotes: 131

Views: 65609

Answers (5)

Washington Botelho
Washington Botelho

Reputation: 732

Rubocop recommends format over sprintf and %. I think it's more intuitive:

format('%02d', 7) # => "07"
format('%02d', 12) # => "12"

Upvotes: 2

Salil
Salil

Reputation: 47472

Try this, it should work:

abc = 5
puts "%.2i" % abc # => 05

abc = 5.0
puts "%.2f" % abc # => 5.00

Upvotes: 12

Ryan Bigg
Ryan Bigg

Reputation: 107718

A lot of people using sprintf (which is the right thing to do), and I think if you want to do this for a string it's best to keep in mind the rjust and ljust methods:

"4".rjust(2, '0')

This will make the "4" right justified by ensuring it's at least 2 characters long and pad it with '0'. ljust does the opposite.

Upvotes: 216

ax.
ax.

Reputation: 59927

how about "%02d" % 9? see http://www.ruby-doc.org/core-2.0/String.html#method-i-25 and http://www.ruby-doc.org/core-2.0/Kernel.html#method-i-sprintf .

Upvotes: 35

Mark Rushakoff
Mark Rushakoff

Reputation: 258138

Did you mean sprintf '%02d', n?

irb(main):003:0> sprintf '%02d', 1
=> "01"
irb(main):004:0> sprintf '%02d', 10
=> "10"

You might want to reference the format table for sprintf in the future, but for this particular example '%02d' means to print an integer (d) taking up at least 2 characters (2) and left-padding with zeros instead of spaces (0).

Upvotes: 157

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