Julia function argument by reference

Question

The docs say

In Julia, all arguments to functions are passed by reference.

so I was quite surprised to see a difference in the behav

Answer 1

In order to mutate each variable inside an array, the broadcast . operation can be used. But be aware that each value inside the array will be changed equally thus there is no need for a for loop.

In the case of adding 1 to each element of an array :

a = rand(1:10, 10)
show(a) = [4, 8, 9, 1, 4, 2, 6, 7, 1, 5]

function add1!(a::Array{Int64})
    a .= a .+ 1
end

add1!(a);
show(a) = [5, 9, 10, 2, 5, 3, 7, 8, 2, 6]

Despite this, if each value of an array is needed to be changed independently then for loop with indices is inevitable.