Hi All,

I've run into a problem and wondered if anyone could help ? I've been programming c on linux for a while now and wanted to try a little c++. Rather than do it as standalone I wanted to call c++ routines from within some existing c code. It seems that can I call the c++ functions as long as they are basically 'c' code. For example:

stuff.cc:

extern "C" {
void startingfn (void) {
printf("hello\n") ;
}
}

and...

stuff.h:

#ifndef _STARTING_H
#define _STARTING_H

extern void startingfn(void) ;

#endif

I can compile this (using gcc - defined in the makefile as used for all the c files) and call the function from my c code (with the stuff.h file included). All's fine, but if I do this:

stuff.cc:

#include <iostream.h>
extern "C" {
void startingfn (void) {
cout << "hello" << endl ;
}
}

it fails with the following message:

/.../libstarting.a(rest.o): In function `startingfn(void)':stuff.o(.text+0x4): undefined reference to `endl(ostream &)'
stuff.o(.text+0xe): undefined reference to `cout'
stuff.o(.text+0x13): undefined reference to `ostream:perator<<(char const *)'
stuff.o(.text+0x1e): undefined reference to `ostream:perator<<(ostream &(*)(ostream &))'
collect2: ld returned 1 exit status
make: *** [gbna] Error 1

I've tried a few variations to work around it but to no avail. I can compile the .cc file with g++ to create a working executable, but I thought this was unneccessary ?

Does the problem lie with the gcc compiler ?

Hoping for an easy solution .

Sure, just compile all your code as C++ code, including the pure C (change its filename extension to .cc or .cpp).

Alex

So, given that I have a large number of exisitng 'c' code files, and I want to add a single 'c++' file into the mix - I'm supposed to rename all my 'c' files and recompile everything ?

Surely there's a better way to do this ?

I wouldn't expect this path to be necessary, for pure business reasons, large amounts of old code sitting around already written and working in 'c' - introduce some 'c++' and everything has to be moved around in this way ? Sounds like an odd way of doing it...?

no, you don't have to rename them, just compile it with a c++ compiler