Leading Zeros

General Usage
1

Hi,

I have a simple question but i cannot find the answer. I have an array of integers between 1 to 999. I need the left pading of 3 so that every element is composed of 3 digits.E.g. [ 001, 002,…090…, 900]. But I would strongly prefer them to be Integers, LPAD() outputs strings.

Is that possible?

2

Looks like you can use the lpad function

lpad(string(n), 3, '0')

You can quickly run this on an entire array with broadcasting

lpad.(string.(v), 3, '0')
3

Where do you want this to happen? When the array is printed?

4

I don’t think that’s possible since 3 == 003. If you have the bitstring for an integer 00000011 is that 3 or 03 or 003…?

Of course, there are ways around that, using a string, making a custom type with the number of leading zeros in it, storing the digits in an array (the digits-function) etc. But none of these are integers.

Maybe we can help you find a good solution if you tell us a little more about why you want it exactly this way; probably there is a good alternative.

5

Sorry, now I think I was confused by the question. I would agree with @giordano the only solution is to do this wherever the output is happening. You don’t want to just make all integers display that way by default, trust me.

6

Hi,

Thanks for the fast reply! if I left pad it to “002”. How can I explode it so it is [‘0’,‘0’,‘2’]?

best,

7 
julia> digits(2, pad = 3)
3-element Array{Int64,1}:
 2
 0
 0
8

collect("002")

9

Although, if you have a number and want digits as numbers, there’s no need to go through strings.

10

wasn’t aware of digits() could work this way as well :slight_smile: thanks!

11 
using Printf
for i in 1:999
    @printf("%03d\n", i)
end
001
002
003 ...

Can also render padded binary output:

    @printf("%6i → %s → %03d\n", i, string(i, base=2, pad=11), i)
end
     1 → 00000000001 → 001
     2 → 00000000010 → 002
     3 → 00000000011 → 003
     4 → 00000000100 → 004
     5 → 00000000101 → 005
     6 → 00000000110 → 006
     7 → 00000000111 → 007 ...