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Date: Sun, 16 May 2004 21:19:41 +0100
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To: Vladimir Zidar <vladimir@mindnever.org>
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Subject: Re: [PHP-DEV] Extension written in C++ and undefined symbols
From: iridium@beyondunreal.com (Peter Waller)

Thank you muchly. It took considerable trial and error but I got it 
working.

For any poor person that ends up searching this list and comes up to 
this thread, in the config.m4 file add the lines

PHP_REQUIRE_CXX
EXTRA_LDFLAGS=-lstdc++

Somewhere.

Also make sure that your file ends in the extension .cpp.

Peter.

Vladimir Zidar wrote:

> When you need to access function compiled from C++ source code, you
>need to declare it as extern "C", in order to tell the compiler to
>generate function name that is compatible with C. Otherwise, compiler
>will generate different name (will mangle it), and C won't be able to
>find it.
>
> So, write
>
>extern "C" blah()
>{
>...
>}
>
>in test.cpp
>
>
>On Sun, 2004-05-16 at 05:08, Peter 'iridium' Waller wrote:
>  
>
>>I've currently got some libraries written in C++ with various class 
>>interfaces, I was going to write an interface between them and PHP but 
>>got very stuck trying to get the extension to recognize any C++ linked 
>>to it at all..
>>
>>I spent quite a while searching the archives and google before posting 
>>this, and found some advice telling me to set EXTRA_LDFLAGS = -lstdc++. 
>>This seemed to fix the odd one or two things, I don't remember what now 
>>because that was a while ago..
>>
>>in my config.m4:
>>
>>PHP_NEW_EXTENSION(nalicity, nalicity.c test.cpp, $ext_shared)
>>
>>in test.cpp:
>>
>>void blah()
>>{
>>   printf( "\n\nBlah\n\n" );
>>}
>>
>>in nalicity.c
>>
>>PHP_FUNCTION(testfunction)
>>{
>>   blah();
>>}
>>
>>Doesn't work unless I rename test.cpp to test.c and change the 
>>PHP_NEW_EXTENSION line accordingly. It compiles fine, I just get the error:
>>
>>/usr/bin/php: relocation error: 
>>/usr/lib/php/extensions/no-debug-non-zts-20020429/../../../../src/php/exts/nalicity/modules/nalicity.so: 
>>undefined symbol: blah
>>
>>when I try to run the PHP and load the dl(). As I said above though, 
>>works fine as a plain old C file. Any ideas? I've stayed up all night 
>>trying to figure it out but have gotten nowhere.
>>
>>(and on an unrelated note, is there any way I can specify an absolute 
>>path to dl()? I feel kinda stupid with all those ../..'s in there.)
>>
>>Thanks in advance for any help,
>>
>>Peter.
>>    
>>