Converting numbers into strings

Question

I need to transform a lot of numbers into strings. The difficult part for me is that all strings must be 4 letters long. For example "1" must be "0001" or "234" must be "0234". I think this is a simple question, but I could not find the answer. Thanks for your help!

Answer 1

As an alternative to sprintf you can use formatC.

For example

> formatC(1:10, width=4, flag="0")
 [1] "0001" "0002" "0003" "0004" "0005" "0006" "0007" "0008" "0009" "0010"

Answer 2

You can use sprintf:

> sprintf("%04d", 1)
[1] "0001"
> sprintf("%04d", c(1, 23, 123))
[1] "0001" "0023" "0123"