Is there any built-in method in RoR to fill zero for integer?

Question

If I want "00001" instead of "1", apart from writing my own filling zero method, is there any built in method can help me fill in zero for the integer?

Answer 1

puts "%05d" % 1    # 00001

See: String::%, Kernel::sprintf

Here's what's going on. The "%05d" to the left of the % is a C style format specifier. The variable on the right side of the % is the thing to be formatted. The format specifier can be decoded like this:

• % - beginning of format specifier
• 0 - Pad with leading zeros
• 5 - Make it 5 characters long
• d - The thing being formatted is an integer

If you were formatting multiple things, you'd put them in an array:

"%d - %s" % [1, "One"]    # => 1 - one