including c headers in c++

[gtg588n]

I am trying to include a C header file in C++, but the C header has some datastructures where some variable names are "namespace" and "this". Obviously C++ complains about the use of these reserved words. I was wondering if there is a way around it besides changing the source code (mainly because I don't have access to the source code, so changing the header files will only create more trouble).

I tried extern "C", but it didn't work.

Below is a small sample code I created that reproduces the problem.

foo.h:

#ifndef __FOO_H
#define __FOO_H
 
typedef struct 
{
   int namespace;
   int this;
} foo_st;
 
void printfoo( foo_st* st );
 
void setfoo( foo_st* st, int n, int t );
 
#endif
 

foo.c:

#include <stdio.h>
#include "foo.h"
 
void setfoo( foo_st* st, int n, int t )
{
   st->namespace = n;
   st->this = t;
}
 
 
void printfoo( foo_st* st )
{
   printf("foo->namespace = %d, foo->this = %d\n", st->namespace, st->this );
}
 

bar.cpp:

#ifdef __cplusplus
extern "C"
{
#endif
#include "foo.h"
#ifdef __cplusplus
}
#endif
int main()
{
   foo_st myfoo;
   setfoo( & myfoo, 4, 5 );
   printfoo( & myfoo );
   return 0;
}
 

I am using gcc 3.3.2 and I compile with:
gcc foo.c -c
gcc bar.cpp foo.o

The error I get is:
In file included from bar.cpp:5:
foo.h:6: error: declaration does not declare anything
foo.h:6: error: syntax error before `namespace'
foo.h:7: error: declaration does not declare anything

(if I change bar.cpp to bar.c, it works as it should)

Can anyone help with that?

[Motoma]

I also get an error, however mine is a little different than yours.
Mine reads:

error: expected unspecified error before "namespace"
error: expected unspecified error before "this"

After having compiled the C code, you no longer need to maintain the invalid names. You can easily change the foo.h struct to :

typedef struct
{
  int ns;
  int th;
} foo_st;
 

And code your C++ files using the new names. I know it's not the best solution, but it reduces the renaming from changing all of your source files to only changing the C++ files.