BetterC, int to string?

[jfondren]

On Friday, 18 June 2021 at 09:05:38 UTC, Mike Brown wrote:
> Hi all,
>
> I would like to convert a D string to an int - im doing this in 
> a compile time function as well. conv throws an error due to it 
> using TypeInfo?
>
> How would I do this?
>
> Kind regards,
> Mike

BetterC has [some CTFE-related 
bugs](https://issues.dlang.org/buglist.cgi?f1=keywords&list_id=236535&o1=allwordssubstr&query_format=advanced&resolution=---&v1=betterC%20CTFE) atm that might be the problem here.

You could if you need betterC use libc at runtime,

```d
extern (C) void main() {
     import core.stdc.stdlib : atoi;
     import core.stdc.stdio : printf;

     const n = atoi("123"); // not enum
     printf("%d\n", n);
}
```

or if you're more concerned about limiting the GC, you can use 
@nogc annotations for that while still having more of the 
language at CTFE and elsewhere:

```d
void main() @nogc nothrow {
     import core.stdc.stdio : printf;
     import std.conv : to;

     enum n = to!int("123"); // not const
     printf("%d\n", n);
}
```

If `n` were const in that last example:

```
exmaple.d(5): Error: `@nogc` function `D main` cannot call 
non- at nogc function `std.conv.to!int.to!string.to`
example.d(5): Error: function `std.conv.to!int.to!string.to` is 
not `nothrow`
example.d(1): Error: `nothrow` function `D main` may throw
```