Hi,

Just started to work with D. Great language.

I want to use C++ libraries for machine learning and deep learning. How do I add C++ libraries to my d code.

For example,

//sample.cpp
#include <iostream>

using namespace std;

int foo(int i, int j, int k)
{
    cout << "i = " << i << endl;
    cout << "j = " << j << endl;
    cout << "k = " << k << endl;

    return 7;
}


//foo.d
extern (C++) int foo(int i, int j, int k);

void main()
{
	foo(1,2,3);
}


How do I compile and link each of them to produce the result?
dmd -c foo.d
gcc -c Sample.cpp

Both of them get me .o files. Where do I go from there?

Thanks,
Siv

On Friday, 27 October 2017 at 17:14:20 UTC, sivakon wrote:
> Hi,
>
> Just started to work with D. Great language.
>
> I want to use C++ libraries for machine learning and deep learning. How do I add C++ libraries to my d code.
>
> For example,
>
> //sample.cpp
> #include <iostream>
>
> using namespace std;
>
> int foo(int i, int j, int k)
> {
>     cout << "i = " << i << endl;
>     cout << "j = " << j << endl;
>     cout << "k = " << k << endl;
>
>     return 7;
> }
>
>
> //foo.d
> extern (C++) int foo(int i, int j, int k);
>
> void main()
> {
> 	foo(1,2,3);
> }
>
>
> How do I compile and link each of them to produce the result?
> dmd -c foo.d
> gcc -c Sample.cpp
>
> Both of them get me .o files. Where do I go from there?
>
> Thanks,
> Siv

This should work:

dmd foo.d Sample.o

Just like the C examples from the D blog:

https://dlang.org/blog/2017/10/25/dmd-windows-and-c/

On Friday, 27 October 2017 at 17:21:39 UTC, Joakim wrote:
>
> This should work:
>
> dmd foo.d Sample.o
>
> Just like the C examples from the D blog:
>
> https://dlang.org/blog/2017/10/25/dmd-windows-and-c/

Just used this! Got this error!

sample.o: In function `foo(int, int, int)':
sample.cpp:(.text+0x17): undefined reference to `std::cout'

On 10/27/17 1:43 PM, sivakon wrote:
> On Friday, 27 October 2017 at 17:21:39 UTC, Joakim wrote:
>>
>> This should work:
>>
>> dmd foo.d Sample.o
>>
>> Just like the C examples from the D blog:
>>
>> https://dlang.org/blog/2017/10/25/dmd-windows-and-c/
> 
> Just used this! Got this error!
> 
> sample.o: In function `foo(int, int, int)':
> sample.cpp:(.text+0x17): undefined reference to `std::cout'

You need to link against the C++ standard library. On my system, it appears to be -lc++.

So in order to pass this value to the linker, use the dmd parameter -L-lc++

In order to find out what the name of the c++ library is, you need to compile a C++ program with the -v option. The linker step will show the library parameters you need to send to dmd.

-Steve

On Friday, 27 October 2017 at 17:43:08 UTC, sivakon wrote:
> On Friday, 27 October 2017 at 17:21:39 UTC, Joakim wrote:
>>
>> This should work:
>>
>> dmd foo.d Sample.o
>>
>> Just like the C examples from the D blog:
>>
>> https://dlang.org/blog/2017/10/25/dmd-windows-and-c/
>
> Just used this! Got this error!
>
> sample.o: In function `foo(int, int, int)':
> sample.cpp:(.text+0x17): undefined reference to `std::cout'

Sorry, just responded quickly from my tablet, didn't try it out first.  There's actually a variant of this sample that is run as a test from the dmd compiler testsuite, so it is checked hundreds of times a day for pending pull requests, on all officially supported platforms by the auto-tester:

https://auto-tester.puremagic.com/pulls.ghtml?projectid=1
https://github.com/dlang/dmd/blob/master/test/runnable/extra-files/cppb.cpp#L41
https://github.com/dlang/dmd/blob/master/test/runnable/cppa.d#L25

Looking at the D script that runs each compiler test, it adds the following flag for all C++ objects:

https://github.com/dlang/dmd/blob/master/test/d_do_test.d#L499

So adding that flag got your example to work for me:

dmd -L-lstdc++ foo.d Sample.o

On Friday, 27 October 2017 at 17:14:20 UTC, sivakon wrote:
> I want to use C++ libraries for machine learning and deep learning. How do I add C++ libraries to my d code.

on FreeBSD, I use:

for C static binding:
----------------------
clang -c sample.c

dmd -L-lc foo.d sample.o
or
ldc -L-lc foo.d sample.o


for c++ static binding:
-----------------------
clang++ -c sample.cpp

dmd -L-lc++ foo.d sample.o
or
ldc -L-lc++ foo.d sample.o


There is nice article here that was pretty interesting too:
https://www.gamedev.net/blogs/entry/2254003-binding-d-to-c/

On Saturday, 28 October 2017 at 02:20:42 UTC, codephantom wrote:
> On Friday, 27 October 2017 at 17:14:20 UTC, sivakon wrote:
>> I want to use C++ libraries for machine learning and deep learning. How do I add C++ libraries to my d code.
>
> on FreeBSD, I use:
>
> for C static binding:
> ----------------------
> clang -c sample.c
>
> dmd -L-lc foo.d sample.o
> or
> ldc -L-lc foo.d sample.o
>
>
> for c++ static binding:
> -----------------------
> clang++ -c sample.cpp
>
> dmd -L-lc++ foo.d sample.o
> or
> ldc -L-lc++ foo.d sample.o
>
>
> There is nice article here that was pretty interesting too:
> https://www.gamedev.net/blogs/entry/2254003-binding-d-to-c/

Thanks! That worked like a charm. Now I can use dlang confidently. Any tips to make it faster cflags etc.