18 Range Over Builtin Types

Intermediate

If a type implements Iterable interface, we can range over it. All data structures in std.collection implement that interface. Therefore we can use for loop to iterate over their elements.

Range over Array.

Range over ArrayList. You shouldnt modify the size of the ArrayList during iteration, because that invalidates iterators.

We use pattern matching to decompose value into key and value. Same note as in ArrayList, we should not add elements during iteration.

Same note as in previous examples.

range_over_builtin_types.cj

import std.collection.*

main() {
    let A = Array<Int64>([1, 2, 3])
    let B = ArrayList<Int64>([4, 5, 6])
    let C = HashMap<Int64, String>([(7, "Ali"), (8, "Isaac"), (9, "Max")])
    let D = HashSet<Int64>([10, 11, 12])

    print("Numbers in Array: ")
    for (i in A) {
        print("${i} ")
    }
    println()

    print("Numbers in ArrayList: ")
    for (i in B) {
        print("${i} ")
    }
    println()

    print("Numbers in HashMap: ")
    for ((key, val) in C) {
        print("(${key},${val}) ")
    }
    println()

    print("Numbers in HashSet: ")
    for (i in D) {
        print("${i} ")
    }
}

// Output:
// Numbers in Array: 1 2 3 
// Numbers in ArrayList: 4 5 6 
// Numbers in HashMap: (7,Ali) (8,Isaac) (9,Max) 
// Numbers in HashSet: 10 11 12