hard20 pts · first answer countsswiftvalue-typesperformance

When a Swift array is copied

When is the array storage actually copied, and what does this code print?

var a = [1, 2, 3]
var b = a      // (1)
b.append(4)    // (2)
print(a.count, b.count)

A.At (1), because assigning an array to a new variable always copies every element right away; it prints 3 4B.At (2), because b is mutated while it still shares storage with a; it prints 3 4C.Never; it prints 4 4D.At (2); it prints 4 4

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