Is this a bug?
julia> s=String[]
String[]
julia> append!(s,"")
String[]
push!
seems to work:
push!(s,"")
1-element Vector{String}:
""
Nevermind, I figured it out.
julia> append!(String[], [""])
1-element Vector{String}:
""
Guess it's the same thing as in
https://discourse.julialang.org/t/tutorial-efficient-and-safe-approaches-to-mutation-in-data-parallelism/62105/4
Probably append!(String[], ("", ))
should work too.
Are you looking for push!
? That is for adding elements whereas append!
iterates the argument and adds the elements in the iterator.
The reason why append!(s, "")
does nothing is that it iterates over the characters in the string, but there are none so nothing happens. If you have a non-empty string it fails since the element type is wrong:
julia> s = String[]
String[]
julia> append!(s, "abc")
ERROR: MethodError: Cannot `convert` an object of type Char to an object of type String
Closest candidates are:
convert(::Type{String}, ::String) at essentials.jl:210
convert(::Type{T}, ::T) where T<:AbstractString at strings/basic.jl:231
convert(::Type{T}, ::AbstractString) where T<:AbstractString at strings/basic.jl:232
...
Stacktrace:
[1] setindex!(A::Vector{String}, x::Char, i1::Int64)
@ Base ./array.jl:839
[2] _append!(a::Vector{String}, #unused#::Base.HasLength, iter::String)
@ Base ./array.jl:991
[3] append!(a::Vector{String}, iter::String)
@ Base ./array.jl:981
[4] top-level scope
@ REPL[2]:1
Not sure I like that it doesn't clean up the pre-allocation when it errors though:
julia> s
3-element Vector{String}:
#undef
#undef
#undef
Thanks to all! I was indeed looking for push!
. What happened is that, by mistake, I read append!(String[], "")
as "append the empty string to String[]
" instead of "append the elements of the empty string to String[]
".
I don't work often on strings and I don't automatically think of them as iterators (yet).
Last updated: Nov 22 2024 at 04:41 UTC