Hello World!
The iter() function generates an iterator trait to
iterate a collection of values by reference.
This includes arrays, vectors, slices, etc.
The function will return an iterator of type T,
where T is the reference type of the elements of the collection.
Iterators have a wide array, pun intended,
of functions to help performing actions on all or specific collection items.
There's the next(), position(), Map, Filter, but most importantly
it can function inside loop structures to define the loop.
The Iterator trait comes with it the position() function that,
with the help of a predicate expression passed into it,
find the index of an item in a collection.
Using the function signature,
Iterator.position(predicate: P) -> Option<usize>,
you simply pass a predicate expression into it and get the index or None in return.
names = ["Bob", "Steve", "Karen", "Lindsey"];
index = names.iter().position(|&n: String| n == "Karen").unrwap();
println!("{} has index of {}", names[index], index)The above code snippet sets up a vector of name strings.
An index is set from calling position with predicate
n == "Karen" from lambda function of arg |&n: String|.
Then the index is found,
since it's found and unwraped it can access the name Karen.