how to rewrite the following for loop in swift 3 syntax?

Question

for (int i = n-2; i >= 0; --i)
{
....
}

the automatic translation of the above to swift 3 syntax is this

for i in n-2 ... 0 
{
}

this doesn't work, because n could be 1, in the c syntax, this is valid, the loop won't be triggered,

but in the swift 3 syntax, this will cause runtime error.

it doesn't cause a runtime error, but it is definitively not equivalent. — Pochi, Jan 04 '17 at 06:40

Alexander · Accepted Answer · 2017-01-04T06:49:09.607

2

for i in stride(from: n-2, through: 0, by: -1) {

}

edited Jan 04 '17 at 06:49

answered Jan 04 '17 at 06:41

Alexander

This never results in `i` being `0`. The to value should be `-1` to have the same functionality as the original post. – nathangitter Jan 04 '17 at 06:45
2

@nathan. Corrected `to:` to `through:` – Alexander Jan 04 '17 at 06:48

score 1 · Answer 2 · answered Jan 04 '17 at 06:43

1

for i in (0 ... n-2).reversed() {

}

answered Jan 04 '17 at 06:43

nathangitter

2 Answers2