Hey all,

How do I get environment variables in a D program? I specifically want the path to a user's home folder.

Ta muchly.

On Sat, Nov 22, 2008 at 12:55 PM, Christopher Wright <dhasenan@gmail.com> wrote:
> Hey all,
>
> How do I get environment variables in a D program? I specifically want the path to a user's home folder.
>
> Ta muchly.
>

In Tango, there's tango.sys.Environment (http://www.dsource.org/projects/tango/docs/current/tango.sys.Environment.html) which provides a nice interface to environment variables.

In Phobos, I think you have to use the C functions to get at environment variables, but std.path.expandTilde can be abused to get the home folder ;)

"Christopher Wright" <dhasenan@gmail.com> wrote in message news:gg9h3f$9uo$1@digitalmars.com...
> Hey all,
>
> How do I get environment variables in a D program?

std.c.stdlib.getenv
http://www.cplusplus.com/reference/clibrary/cstdlib/getenv.html

> I specifically want the path to a user's home folder.

Platform-dependent.

For Windows, you can use the concatenation of HOMEDRIVE and HOMEPATH, but I don't know under which versions of Windows these variables are actually set.

----------
import std.c.stdlib, std.string, std.stdio;

void main() {
   string homeDrive, homePath;
   homeDrive = toString(getenv("HOMEDRIVE")).dup;
   homePath = toString(getenv("HOMEPATH")).dup;

   writefln("%s%s", homeDrive, homePath);
}
----------

For Unix, I'm informed that the HOME environment variable does it.
http://unix.derkeiler.com/Newsgroups/comp.unix.programmer/2005-09/0092.html

HTH

Stewart.

-- 
My e-mail address is valid but not my primary mailbox.  Please keep replies on the 'group where everybody may benefit. 

Jarrett Billingsley wrote:
> On Sat, Nov 22, 2008 at 12:55 PM, Christopher Wright <dhasenan@gmail.com> wrote:
>> Hey all,
>>
>> How do I get environment variables in a D program? I specifically want the
>> path to a user's home folder.
>>
>> Ta muchly.
>>
> 
> In Tango, there's tango.sys.Environment
> (http://www.dsource.org/projects/tango/docs/current/tango.sys.Environment.html)
> which provides a nice interface to environment variables.
> 
> In Phobos, I think you have to use the C functions to get at
> environment variables, but std.path.expandTilde can be abused to get
> the home folder ;)

Thanks, that's exactly what I was looking for.

I thought (perhaps wrongly) C allowed you to declare main as taking a list of environment variables, which is why I asked here rather than Tango's forums. But D doesn't, so I probably should have asked at the library-specific forums.

Reply to Christopher,

> I thought (perhaps wrongly) C allowed you to declare main as taking a
> list of environment variables,

It does.

>     homeDrive = toString(getenv("HOMEDRIVE")).dup;
>     homePath = toString(getenv("HOMEPATH")).dup;

don't forget, that D char[] is utf8 and windows char* is 8-bit chars, not utf8.
so you should import std.windows.charset and use toMBSz() as D->WindowsAPI and fromMBSz as WindowsAPI->D string converter. for example:
homeDrive = fromMBSz(getenv("HOMEDRIVE")).dup;

"novice2" <sorry@noem.ail> wrote in message news:ggbd96$2drl$1@digitalmars.com...
>>     homeDrive = toString(getenv("HOMEDRIVE")).dup;
>>     homePath = toString(getenv("HOMEPATH")).dup;
>
> don't forget, that D char[] is utf8 and windows char* is 8-bit chars, not utf8.
> so you should import std.windows.charset and use toMBSz() as D->WindowsAPI and fromMBSz as WindowsAPI->D string converter. for example:
> homeDrive = fromMBSz(getenv("HOMEDRIVE")).dup;

Under what setups can the drive letter be a non-ASCII character?

But according to my experiments, getenv works in the OEM encoding rather than the Windows encoding, so you'd need

   homePath = fromMBSz(getenv("HOMEPATH"), 1).dup;

If you want to make sure all Unicode characters are preserved, you're best off using the Windows API

   wchar[] wpath;
   wpath.length = GetEnvironmentVariableW("HOMEPATH", null, 0);
   GetEnvironmentVariableW("HOMEPATH", wpath.ptr, wpath.length);

Stewart.

-- 
My e-mail address is valid but not my primary mailbox.  Please keep replies on the 'group where everybody may benefit. 

Christopher Wright wrote:
> Hey all,
> 
> How do I get environment variables in a D program? I specifically want the path to a user's home folder.
> 
> Ta muchly.

I think the 'correct' way on Windows is to use SHGetSpecialFolderPathA.

Something like this:

char[MAX_PATH] buf;
SHGetSpecialFolderPathA(null, buf.ptr, CSIDL_PERSONAL, false);
char[] dir = toString(buf.ptr);

or CSIDL_APPDATA, etc.

torhu wrote:

> Christopher Wright wrote:
>> Hey all,
>> 
>> How do I get environment variables in a D program? I specifically want the path to a user's home folder.
>> 
>> Ta muchly.
> 
> I think the 'correct' way on Windows is to use SHGetSpecialFolderPathA.
> 
> Something like this:
> 
> char[MAX_PATH] buf;
> SHGetSpecialFolderPathA(null, buf.ptr, CSIDL_PERSONAL, false);
> char[] dir = toString(buf.ptr);
> 
> or CSIDL_APPDATA, etc.

In tango this is available in tango.sys.win32.SpecialPath

-- 
Lars Ivar Igesund
blog at http://larsivi.net
DSource, #d.tango & #D: larsivi
Dancing the Tango

> Under what setups can the drive letter be a non-ASCII character?
any non-english windows have folders, usernames, etc with non-ascii chars, therefore this names presents in environment, registry, file API etc.

>     wchar[] wpath;
>     wpath.length = GetEnvironmentVariableW("HOMEPATH", null, 0);
>     GetEnvironmentVariableW("HOMEPATH", wpath.ptr, wpath.length);

i am afraid that windows API named *W works with UCS2 string.
but D wchar[] is UTF-16. since UCS2 is some sort of subset of UTF-16, then your code above is correct (then lvalue is D wchar[]).
but problems can appear in reverse situation - pass D wchar[] to windows API.

that is why utf strings in D annoy me - because all strings exchange D<->WindowsAPI shoud be passed thru to-utf and from-utf convertion. other programming languages works fine with windows, not required utf-support editors etc. sorry for offtopic.