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Function `object.reserve`

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.


						
				size_t reserve(T)
				(
				

				  ref T[] arr,
				

				  size_t newcapacity
				

				) pure nothrow @trusted;

Returns

The new capacity of the array (which may be larger than the requested capacity).

Example

//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.ptr !is slice.ptr);
writeln(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.ptr;
u = a.capacity;
a ~= [5, 6, 7, 8];
assert(p == a.ptr);      //a should not have been reallocated
assert(u == a.capacity); //a should not have been extended

Authors

Walter Bright, Sean Kelly

License

Boost License 1.0.