need help on gfortran and C++

[Tobias Burnus]

On 01/11/2012 08:33 AM, Mojtaba Seifi wrote:
> But I get the following error:
> main.cpp:(.text+0x41): undefined reference to `MULTAB_'
>
> extern "C" int MULTAB_(int&a, int&b);
>
> INTEGER FUNCTION MULTAB(A, B)

In gfortran, the "function multab" translates into "multab_" and not 
"MULTAB_". You have to change the 'extern "C"' declaration to lower case.

(It depends on the Fortran compiler and the used options whether the 
symbol becomes lower or upper case and whether it has one, two or no 
trailing underscores.)


I assume that it is sufficient for you to change the name in the C++ 
file. However, I want to point out that Fortran also provides means for 
better interoperability with C ["bind(C)"] - and thus with C++'s 'extern 
"C"', cf. 
http://gcc.gnu.org/onlinedocs/gfortran/Mixed_002dLanguage-Programming.html

Additionally, I want to point out that without using Bind(C) there might 
be additional issues - and differences between compilers; in particular, 
the way, "float"/"REAL" values and complex-number-returning functions 
are implemented, differs among compilers.

Tobias