I feel dumb, because this can't be as elusive as it feels.

I'm calling a C library function, and getting a char * (null terminated).

Now I want it to be a D string. What's the right way to do this? Performance and memory use are not important; I just want a simple and idiomatic way to get from point A to point B.

TIA,
Andy

On Wednesday, 7 May 2025 at 22:23:36 UTC, Andy Valencia wrote:

https://dlang.org/library/std/string/from_stringz.html

for the opposite see https://dlang.org/library/std/string/to_stringz.html

On Wednesday, 7 May 2025 at 22:28:32 UTC, Dejan Lekic wrote:

Given that fromStringz returns a slice of the original string, you can use std.conv.to to do it with an allocation when needed: to!string(str).

On Wednesday, 7 May 2025 at 22:28:32 UTC, Dejan Lekic wrote:

So about fromStringz...

import std.string : fromStringz;
import core.stdc.time : ctime;

void
main() {
    string s = fromStringz(ctime(null));
}

Like that?

tst44.d(6): Error: cannot implicitly convert expression fromStringz(ctime(null)) of type char[] to string

Still seeking...

On Wednesday, 7 May 2025 at 22:47:35 UTC, Andy Valencia wrote:

import std.string : fromStringz;
import core.stdc.time : ctime;

void
main() {
    string s = fromStringz(ctime(null));
}

fromStringz is giving you a slice of a char*, typed char[].

string is immutable(char)[], so you can't assign char[] to it.

You could:

• change the type of s to char[]
• call .idup on the array returned from fromStringz to allocate a string
• use std.conv.to

On Thursday, 8 May 2025 at 00:53:20 UTC, Mike Parker wrote:

Thank you. I want to work in strings, so the first one's not an option. But both the second and third do the trick. Would you say the to!string would be the most idiomatic? It worked as "to!string(ctime(&t))", but is it safe to assume it's reliably dealing with null-terminated strings? It's the pithiest if so.

Andy

On Thursday, 8 May 2025 at 04:51:27 UTC, Andy Valencia wrote:

Yes, it'safe to assume:

https://github.com/dlang/phobos/blob/12bcacca2a590942e1b917daaa8732a509b2ef30/std/conv.d#L1087