• Dfr (13/13) Dec 13 2013 Hello
• Ithy (2/15) Dec 13 2013 Try using cast(char*)pattern
• Jonathan M Davis (14/33) Dec 13 2013 The problem is that toStringz returns immutable(char)* (because string i...
• Mike Parker (14/26) Dec 13 2013 Declare the function to like so:
• Jonathan M Davis (6/9) Dec 14 2013 Wait. That was stupid of me. Don't do this. It'll give you a char*, but ...

"Dfr" <deflexor yandex.ru> writes:

Hello

I trying to write simple wrapper around pcre and have problem 
passing strings to it. As i understood, the best way is  
std.string.toStringZ.

So, my code look like:

string pattern = "....";
pcre_compile2( toStringz(pattern), options, &errcode, &errmsg, 
&erroffset, cast(char*)null);

This gives me error:

Error: function pcre_compile2 (char*, int, int*, char**, int*, 
char*) is not callable using argument types (immutable(char)*, 
int, int*, char**, int*, char*)

Any ideas for better way to do this task ?

"Ithy" <n n.n> writes:

On Friday, 13 December 2013 at 08:00:21 UTC, Dfr wrote:
 Hello

 I trying to write simple wrapper around pcre and have problem 
 passing strings to it. As i understood, the best way is  
 std.string.toStringZ.

 So, my code look like:

 string pattern = "....";
 pcre_compile2( toStringz(pattern), options, &errcode, &errmsg, 
 &erroffset, cast(char*)null);

 This gives me error:

 Error: function pcre_compile2 (char*, int, int*, char**, int*, 
 char*) is not callable using argument types (immutable(char)*, 
 int, int*, char**, int*, char*)

 Any ideas for better way to do this task ?

Try using cast(char*)pattern

Jonathan M Davis <jmdavisProg gmx.com> writes:

On Friday, December 13, 2013 09:00:20 Dfr wrote:
 Hello
 
 I trying to write simple wrapper around pcre and have problem
 passing strings to it. As i understood, the best way is
 std.string.toStringZ.
 
 So, my code look like:
 
 string pattern = "....";
 pcre_compile2( toStringz(pattern), options, &errcode, &errmsg,
 &erroffset, cast(char*)null);
 
 This gives me error:
 
 Error: function pcre_compile2 (char*, int, int*, char**, int*,
 char*) is not callable using argument types (immutable(char)*,
 int, int*, char**, int*, char*)
 
 Any ideas for better way to do this task ?

The problem is that toStringz returns immutable(char)* (because string is 
immutable(string)[]), and your function is taking char*. It will work to pass 
the result of toStringz to a C function which takes const char* (since 
immutable will implicitly convert to const), but immutable doesn't implicitly 
convert to mutable, and casting immutable mutable is almost always a bad idea.

The easiest solution would be to use std.utf.toUTFz. e.g.

auto cstr = str.toUTFz!(char*)();

or you could do something like

auto cstr = str.dup.ptr;

In either case, what you're doing is allocating a new char[] which holds the 
same elements as the original string and getting its ptr property so that you 
have a char*.

- Jonathan M Davis

Mike Parker <aldacron gmail.com> writes:

On 12/13/2013 5:00 PM, Dfr wrote:
 Hello

 I trying to write simple wrapper around pcre and have problem passing
 strings to it. As i understood, the best way is std.string.toStringZ.

 So, my code look like:

 string pattern = "....";
 pcre_compile2( toStringz(pattern), options, &errcode, &errmsg,
 &erroffset, cast(char*)null);

 This gives me error:

 Error: function pcre_compile2 (char*, int, int*, char**, int*, char*) is
 not callable using argument types (immutable(char)*, int, int*, char**,
 int*, char*)

 Any ideas for better way to do this task ?

Declare the function to like so:

pcre* pcre_compile2( const(char)*, int, int*, const(char)**, int*, 
const(ubyte)*);

This matches the C declaration according to [1]. immutable args can be 
passed to const params without seeing your error. Also, note the last 
paramters. In C, it's declared to be const unsigned char* and the 
documentation suggest it's intended to be treated as a byte array rather 
than a string. In that case, const(ubyte)* is the appropriate choice. D 
declarations of C functions should generally match the C version as 
closely as possible, including use of const, but with intent taken into 
account as well (e.g. byte array vs string).

[1] 
https://code.google.com/p/wiimc/source/browse/trunk/libs/pcre/doc/html/pcre_compile2.html?r=423

"Jonathan M Davis" <jmdavisProg gmx.com> writes:

On Friday, December 13, 2013 01:17:41 Jonathan M Davis wrote:
 or you could do something like
 
 auto cstr = str.dup.ptr;

Wait. That was stupid of me. Don't do this. It'll give you a char*, but it 
won't be null-terminated. If you need char*, then use toUTFz!(char*) - though 
from what Mike's saying, it sounds like the problem was really your function 
prototype, which was supposed to take const char* rather than char*.

- Jonathan M Davis