Looping through an array in Q#

Question

How to loop through the elements of an array and access them by their index in Q# language since the conventional looping in C++ doesn't work here.

Answer 1

Suppose the array is arr = T[], where T is any type in Q#.

let n = Length(arr);
for (i in 0 .. (n-1)) {
     // use the element arr[i]
}

It is to be noted that if arr is defined using 'let' then the values are immutable and can be accessed but not assigned. If it is defined using 'mutable' literal then the elements can also be set using the 'set' keyword. In that case define the array is follows

mutable arr = new T[N] 

where N is the length required.