On 2013-02-02 22:33, Steven Schveighoffer wrote:
Heap block sizes start at 16. One byte overhead is used to store the array
length, so the minimum size of ANY array allocation is 15 bytes.
How is the length stored because I see only strange numbers in that byte.
foreach (end; 2..31) {
ubyte[] x;
foreach (i; 0..end) {
x ~= cast(ubyte)i;
}
writeln(x.length, " ", x.capacity, " ", x.ptr[end]);
}
That code outputs following length/capacity/extra_byte:
2 15 69
3 15 0
4 15 100
5 15 26
6 15 36
7 15 0
8 15 0
9 15 0
10 15 0
11 15 0
12 15 0
13 15 0
14 15 0
15 15 15
16 31 0
17 31 0
18 31 0
19 31 0
20 31 0
21 31 0
22 31 0
23 31 0
24 31 0
25 31 0
26 31 0
27 31 0
28 31 0
29 31 0
30 31 0
Last byte's value for length == 2 is quite random on each execution.
In a smaller way also for length == 6. Other values seem constant.
