On Friday, 24 November 2023 at 09:35:00 UTC, BoQsc wrote:
I tried to look into https://dlang.org/phobos/std_conv.html
Most of the functions inside `std.conv` seem to be dependant on
[Garbage Collection](https://dlang.org/spec/garbage.html).
And I couldn't find a straightforward way to produce a `string`
value out of `uint` value.
How to convert or parse `uint` value to a `string` in `@nogc`
way?
There are various tricks to do such conversion very fast. For
example, the following article is essential for implementing it:
https://lemire.me/blog/2021/06/03/computing-the-number-of-digits-of-an-integer-even-faster/
Rather than doing conversion one digit at a time, it's much more
efficient to process multiple digits per loop iteration. Consider
an illustrative pseudocode like this:
```D
while (x >= 100) {
write(twodigits_lookup_table[x % 100]); // we can handle
two digits at once
x /= 100;
}
```
I have a @nogc compatible DUB module, which implements fast
formatted output to stdout: https://github.com/ssvb/speedy-stdio
(cutting some corners allows to squeeze some extra performance
out of it).
The same code can be adapted to do formatted output to a memory
buffer as well.
