The new capacity of the array (which may be larger than the requested capacity).
//Static array slice: no capacity. Reserve relocates. int[4] sarray = [1, 2, 3, 4]; int[] slice = sarray[]; auto u = slice.reserve(8); assert(u >= 8); assert(&sarray[0] !is &slice[0]); assert(slice.capacity == u); //Dynamic array slices int[] a = [1, 2, 3, 4]; a.reserve(8); //prepare a for appending 4 more items auto p = &a[0]; u = a.capacity; a ~= [5, 6, 7, 8]; assert(p == &a[0]); //a should not have been reallocated assert(u == a.capacity); //a should not have been extended
Reserves capacity for a slice. The capacity is the size that the slice can grow to before the underlying array must be reallocated or extended.