Number to string with leading (left padded) zeros in Julialang

Question

It seems as an easy question, but I cannot find the answer anywhere. If I have an integer variable, how can I transform it to a string with leading zeros?

I want something as the code below:

n = 4
string_size = 3
println(fleading(n, string_size)) 
# result should be "004"

Where fleading would be something like the function to transform the number to string with leading zeros. The analogous way in python is str(4).zfill(3) which gives 004 as result.

Michael Ohlrogge · Accepted Answer · 2019-09-05T11:43:07.743

29

You're looking for the lpad() (for left pad) function:

julia> lpad(4,3,"0")
"004"

Note the last argument must be a string.

From the documentation:

lpad(string, n, "p")

Make a string at least n columns wide when printed, by padding on the left with copies of p.

edited Sep 05 '19 at 11:43

answered Aug 24 '16 at 19:46

Michael Ohlrogge

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Thanks! looking for leading zeros didn't get me any result. – silgon Aug 24 '16 at 19:49
@silgon Yeah, it's tricky to know all the different terminology people use to refer to this kind of stuff – Michael Ohlrogge Aug 24 '16 at 19:49
Now it has to be `lpad(4,3,"0")` as the last one has to be a string, – Wikunia Sep 04 '19 at 22:38

score 5 · Answer 2 · answered Feb 08 '19 at 11:46

5

For Julia 1.0 the syntax is:

lpad(s, n::Integer, p::Union{AbstractChar,AbstractString}=' ')

The example is therefore:

julia> lpad(4, 3, '0')
004

answered Feb 08 '19 at 11:46

Martin

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Thanks! Docs link: https://docs.julialang.org/en/v1/base/strings/#Base.lpad – captainpete Sep 02 '21 at 12:40

score 2 · Answer 3 · answered Apr 27 '21 at 17:49

2

There is also @printf("%03i",4) using Printf.@printf

answered Apr 27 '21 at 17:49

tlamadon

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Number to string with leading (left padded) zeros in Julialang

3 Answers3