It is used in the code:
tt=Array{Int64}(undef,0)
but the following error is shown:
UndefVarError: undef not defined
would you please say why it happened? and is there any alternative for the code?
If you want an empty vector just write (should work in very old and new Julia):
tt = Int64[]
or even tt = Int[] if you are on a system with 64 bit ints (which is almost always true)