Julia: The value unicodeerror of Chinese string and its solution _unicode

In Julia, the value of a Unicode string may be accidentally a pit.
Thanks to @gnimuc, provide the following links that can be done as a reference.
Http://stackoverflow.com/questions/39501900/truncate-string-in-julia

I. Questions and Suggestions

Julia> STRs = "#我是中国人"
"#我是中国人"

julia> strs[1:1]
"#"

julia> Strs[2:2]
"I"

Julia > Strs[3:3]
ERROR:UnicodeError:invalid character index
 in GetIndex (:: String,:: Unitrange{int64}) at. \ strings\string.jl:130

julia> Strs[4:4]
ERROR:UnicodeError:invalid character index in
 getindex (:: String,:: Unitrange{int64}) at. \strings\string.jl:130

julia> Length (STRs)
6

Second, train of thought
If you get a value similar to Strs[3:3], what's the solution? String => character array first ...?

Julia> Data =collect (Take (Strs,length (STRs)))
6-element array{char,1}:
 ' # '
 i '
 is '
 in '
 ' country '
 people '
julia> data2= Vector{char} (STRs) # This is an alternative way 
6-element array{char,1}:
 ' # '
 i '
 ' is '
 in ' the '
 country '
 person '

julia> str =string (Data[2:4])
' [' I ', ' yes ', ' in '] '

julia> Str =string (data[4])
"in"

julia> str =string (DATA[2:4)) # recommended scheme, String PK string
"I am Medium"

julia> Str =string (Data[2:4] ...) # Alternative
' I'm in '

julia> str =string (Data[1:2])
"#我"

julia> str =string (data[2:2))
"I"

Third, the optimization plan

Now encapsulated as a custom function:

Julia> getstrs (strs::string) =collect (Take (Strs,length (STRs)))
getstrs (generic function with 1 method)

Julia> getindexstrs (strs::string,n,m) =string (Getstrs (STRs) [n:m]) # String!
Getindexstrs (Generic function with 1 method)

julia> getindexstrs (strs::string,n) =getindexstrs (strs,n,n)
getindexstrs (generic function with 2)

Efficiency optimization

function StringIndex (strs::string,n,m)
    if Isascii (STRs) return
        strs[n:m]
    else return
        getindexstrs ( STRS,N,M) End-end
stringindex (strs,n) =stringindex (strs,n,n);

Four, test

Julia> getindexstrs (strs,1,3)
"#我是"

julia> getindexstrs (strs,1,1)
"#"

julia> Getindexstrs (strs,3,3)
"is"

julia> getindexstrs (strs,2,4)
"I am Medium"

julia> getindexstrs ( strs,5) "
country"

julia> getindexstrs (strs,4)
"

julia> getindexstrs (strs,3)
" is "

Julia> StringIndex ("Q I am Chinese", 1,5) #isascii->false
"Q I am China"

julia> stringindex ("QABSCDSD", 2, 3) # Isascii->true
"AB"

There may be other ways (including form and performance may be different, such as Vector{char} (STRs)), but this approach is relatively simple and easy to understand.