How to replace the charactors in the string?

General Usage
11

try this

# Implement Perl tr function
function perl_tr(s::AbstractString, target::AbstractString, rep::AbstractString)
    @assert length(target) == length(rep)
    Base.replace(collect(s), Dict(zip(target,rep))...) |> join
end

let
    mystring = "The cat sat on the mat"
    mystring = perl_tr(mystring,"ao","oL")
    println(mystring)
end

typecasting it to AbstractString could make it faster.