• =?UTF-8?B?Ik5vcmRsw7Z3Ig==?= (13/13) Nov 30 2013 I'm struggling to call mktemp in D:
• Dicebot (10/13) Nov 30 2013 AFAIR, this should work:
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (5/9) Nov 30 2013 However, I doubt that .dup copies that '\0' character. Although the
• Dicebot (5/9) Nov 30 2013 Hm, yes, this also sounds like a valid concern. I thought that
• Adam D. Ruppe (26/29) Nov 30 2013 This is because mktemp needs to write to the string. From
• Dicebot (4/5) Nov 30 2013 Ah disregard my post then, I thought it is yet another C function
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (4/6) Nov 30 2013 Because char.init is not 0 in D: :)

=?UTF-8?B?Ik5vcmRsw7Z3Ig==?= <per.nordlow gmail.com> writes:

I'm struggling to call mktemp in D:

     import core.sys.posix.stdlib;
     import std.string: toStringz;
     auto name = "alpha";
     auto tmp = mktemp(name.toStringz);

but I can't figure out how to use it so DMD complains:

     /home/per/Work/justd/fs.d(1042): Error: function 
core.sys.posix.stdlib.mktemp (char*) is not callable using 
argument types (immutable(char)*)

How do I create a mutable zero-terminated C-style string?

I think I've read somewhere that string literals (`const` or 
`immutable`) are implicitly convertible to zero (null)-terminated 
strings.

"Dicebot" <public dicebot.lv> writes:

On Saturday, 30 November 2013 at 15:48:28 UTC, Nordlöw wrote:
 I think I've read somewhere that string literals (`const` or 
 `immutable`) are implicitly convertible to zero 
 (null)-terminated strings.

AFAIR, this should work:

char[] name = "alpha".dup;
mktemp(name.ptr);

D literals are zero-terminated so toStringz is only needed if you 
want to pass to C function slice of literal or some runtime input.

Another option is to declare extern(C) function to take `const 
(char)*` argument, as far as I remember C it should not affect 
mangling but will allow to pass literal directly without 
allocating a mutable copy.

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 11/30/2013 07:58 AM, Dicebot wrote:

 char[] name = "alpha".dup;
 mktemp(name.ptr);

 D literals are zero-terminated so toStringz is only needed if you want
 to pass to C function slice of literal or some runtime input.

However, I doubt that .dup copies that '\0' character. Although the 
literal has the termination, we are in slice land beyond that literal so 
the termination must somehow be ensured.

Ali

"Dicebot" <public dicebot.lv> writes:

On Saturday, 30 November 2013 at 18:58:30 UTC, Ali Çehreli wrote:
 However, I doubt that .dup copies that '\0' character. Although 
 the literal has the termination, we are in slice land beyond 
 that literal so the termination must somehow be ensured.

 Ali

Hm, yes, this also sounds like a valid concern. I thought that 
for literals \0 is part of actual string but after making a quick 
check it looks "hidden" behind actual length. So yep, perfectly 
wrong answer from me :)

"Adam D. Ruppe" <destructionator gmail.com> writes:

On Saturday, 30 November 2013 at 15:48:28 UTC, Nordlöw wrote:
     /home/per/Work/justd/fs.d(1042): Error: function 
 core.sys.posix.stdlib.mktemp (char*) is not callable using 
 argument types (immutable(char)*)

This is because mktemp needs to write to the string. From 
mktemp(3):

  The last six characters of template must be  XXXXXX  and  these
  are  replaced  with  a string that makes the filename unique.  
Since it
  will be modified, template must not be a string constant, but 
should be
  declared as a character array.



So what you want to do here is use a char[] instead of a string. 
I'd go with:


import std.stdio;

void main() {
	import core.sys.posix.stdlib;

         // we'll use a little mutable buffer defined right here
	char[255] tempBuffer;
	string name = "alphaXXXXXX"; // last six X's are required by 
mktemp
	tempBuffer[0 .. name.length] = name[]; // copy the name into the 
mutable buffer
	tempBuffer[name.length] = 0; // make sure it is zero terminated 
yourself

	auto tmp = mktemp(tempBuffer.ptr);
	import std.conv;
	writeln(to!string(tmp));
}

"Dicebot" <public dicebot.lv> writes:

On Saturday, 30 November 2013 at 15:59:38 UTC, Adam D. Ruppe 
wrote:
 This is because mktemp needs to write to the string.

Ah disregard my post then, I thought it is yet another C function 
that misses `const` in signature :)

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 11/30/2013 07:59 AM, Adam D. Ruppe wrote:

      tempBuffer[name.length] = 0; // make sure it is zero terminated
 yourself

Because char.init is not 0 in D: :)

     assert(tempBuffer[name.length + 1] == '\xff');

Ali