Hi,

(I'm french, sorry for my bad english)

The following doesn't compile :

import std.stdio;

void bar(void* str)
{
	writefln(cast(char[]) str);
}

void main()
{
	char[] foo;

	foo = "Hello world";

	bar(cast(void*) foo);
}

$ dmd void.d
void.d(5): Error: e2ir: cannot cast from void* to char[]

How should I write it to make it work ?

e-t172 wrote:
> Hi,
> 
> (I'm french, sorry for my bad english)
> 
> The following doesn't compile :
> 
> import std.stdio;
> 
> void bar(void* str)
> {
>     writefln(cast(char[]) str);
> }
> 
> void main()
> {
>     char[] foo;
> 
>     foo = "Hello world";
> 
>     bar(cast(void*) foo);
> }
> 
> $ dmd void.d
> void.d(5): Error: e2ir: cannot cast from void* to char[]
> 
> How should I write it to make it work ?

<obvious>
Remove the casts and change the argument type of bar to char[]:
---
import std.stdio;

void bar(char[] str)
{
    writefln(str);
}

void main()
{
    char[] foo;

    foo = "Hello world";

    bar(foo);
}
---
</obvious>


Alternatives:

Arrays need a length, which you could also pass separately:
---
import std.stdio;

void bar(size_t length, void* str)
{
    writefln((cast(char*) str)[0 .. length]);
}

void main()
{
    char[] foo;

    foo = "Hello world";

    bar(foo.length, cast(void*) foo);
}
---


If you insist on passing a C-style string in a void* :
---
import std.stdio;
import std.string;

void bar(void* str)
{
    // Convert back to char[] and write to console
    writefln(toString(cast(char*) str));
}

void main()
{
    char[] foo;

    foo = "Hello world";

    // Ensure presence of 0-terminator
    // (This is not necessary for string literals in current DMD
    // versions, but relying on this is a very bad habit. Also, it
    // would break if you ever try to pass a string not directly
    // initialized by a string literal)
    bar(toStringz(foo));
}
---

e-t172 escribió:
> Hi,
> 
> (I'm french, sorry for my bad english)

I've seen a lot of people saying this same phrase. I think you should not say that. Most of the native english speakers doesn't make even a little effort to learn other languages, so why you should say sorry?

Frits van Bommel a écrit :
> Arrays need a length, which you could also pass separately:
> ---
> import std.stdio;
> 
> void bar(size_t length, void* str)
> {
>     writefln((cast(char*) str)[0 .. length]);
> }
> 
> void main()
> {
>     char[] foo;
> 
>     foo = "Hello world";
> 
>     bar(foo.length, cast(void*) foo);
> }
> ---

Thanks :)

Ary Manzana wrote:
> e-t172 escribió:
>> Hi,
>>
>> (I'm french, sorry for my bad english)
> 
> I've seen a lot of people saying this same phrase. I think you should not say that. Most of the native english speakers doesn't make even a little effort to learn other languages, so why you should say sorry?

In fact, on some sites I read I've seen people claiming to be native English speakers with seemingly worse English skills than the average person using such a phrase. :)