Hans Olsson wrote:

> * What is specified about math-functions (in <cmath>).
> In CD2 it is implementation-defined if they are extern "C" or extern "C++"
> and constructing a table of pointers to them is thus not possible.

Implementors are encouraged to make them C++ functions,
but that's _not_ required.

As ever, directly taking a pointer to a C library function
is unportable:

char* (*p) (char*, const char*) = &std::strcpy; // unportable

You can wrap the fucntion:

char* my_strcpy (char*, const char*);
char* (*p) (char*, const char*) = my_strcpy; // ok

Note that by wraping the function you can also use other
arguments or return types:

void my_strcpy (char*, const char*);
void (*p) (char*, const char*) = my_strcpy; // ok

Or you can use overloading:

extern "C"
typedef char* (*c_func) (char*, const char*);

extern "C++" // extern directive is redondant here
typedef char* (*cpp_func) (char*, const char*);

void use_func (c_func);
void use_func (cpp_func);

--

Valentin Bonnard                mailto:bonnardv@pratique.fr
info about C++/a propos du C++: http://pages.pratique.fr/~bonnardv/


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