Difference between var array and let array?

Question

I'm studying arrays in Swift and in my book first they write:

let numbers = [0, 1, 2, 3]

but then write:

var numbers = [0, 1, 2, 3]

I know that let denotes constants and var refers to variables, but practically what changes from an array declared as constant and an array declared as variable?

@Rob how is the link a duplicate? it talks about scope of var/let in javascript — giorashc, Sep 05 '19 at 14:43

score 5 · Accepted Answer · answered Jul 07 '19 at 11:56

5

since arrays in swift are structs declaring an array with let not only prevents you from assigning a new value to it but also prevents you from changing its contents

so for example:

    let arr = [0, 1, 2]
    arr[0] = 10 //will not compile
    arr = [] //will not compile

answered Jul 07 '19 at 11:56

giorashc

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Thank you, all answers are good and useful but in my opinion yours is more complete. Solved! – Bug-Gy Jul 07 '19 at 12:07

score 2 · Answer 2 · answered Jul 07 '19 at 11:57

2

The array declared as constant is immutable.

Its size and contents cannot be changed.

answered Jul 07 '19 at 11:57

bart

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score 1 · Answer 3 · answered Jul 07 '19 at 11:58

1

you can not change/add/remove elements of array when it is declared with let. if you want make any changes with an array, you need to declare with var.

answered Jul 07 '19 at 11:58

Li Jin

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Difference between var array and let array?

3 Answers3