On Thursday, 20 January 2022 at 12:15:56 UTC, forkit wrote:
void createUniqueIDArray(ref int[] idArray, int recordsNeeded)
{
idArray.reserve(recordsNeeded);
debug { writefln("idArray.capacity is %s",
idArray.capacity); }
// id needs to be 9 digits, and needs to start with 999
// below will contain 1_000_000 records that we can choose
from.
int[] ids = iota(999_000_000, 1_000_000_000).array; //
NOTE: does NOT register with -profile=gc
int i = 0;
int x;
while(i != recordsNeeded)
{
x = ids.choice(rnd);
// ensure every id added is unique.
if (!idArray.canFind(x))
{
idArray ~= x; // NOTE: does NOT register with
-profile=gc
i++;
}
}
}
Allocating 4 megs to generate 10 numbers??? You can generate a
random number between 999000000 and 1000000000.
```
immutable(int)[] createUniqueIDArray(int recordsNeeded)
{
import std.random;
import std.algorithm.searching : canFind;
int[] result = new int[recordsNeeded];
int i = 0;
int x;
while(i != recordsNeeded)
{
// id needs to be 9 digits, and needs to start with 999
x = uniform(999*10^^6, 10^^9);
// ensure every id added is unique.
if (!result[0 .. i].canFind(x))
result[i++] = x;
}
import std.exception : assumeUnique;
return result.assumeUnique;
}
void main()
{
import std.stdio;
createUniqueIDArray(10).writeln;
}
```
Only one allocation, and it would be tracked with -profile=gc...
