Calling C++ function from C code linkage errors (using gcc for linking)

I am writting a "library" in C++ that is supposed to be used also by C code. I have followed the process as such:
- Using g++ and gcc compilers (as they are compatible).
- Used extern "C" in functions to be used by C code.
- My top level uses a wrapper function with signature that can be understood by a C compiler.
- Compiled to objective files the C++ code (with g++).
- Compiled my client code file with gcc.
- Edit: Tried/want to link them with gcc (or ld) (and not g++).

An MCV example would be the following:

mymalloc.h

#include <stdlib.h> /* for size_t */

#ifdef __cplusplus
extern "C"
#endif
void *mymalloc(size_t cbytes);

#ifdef __cplusplus
extern "C"
#endif
void myfree(void *ptr);

allocator.cpp

#include "allocator.h"
#include "mymalloc.h"

Allocator *  Allocator::instance = 0;

extern "C" void *mymalloc(size_t cbytes){
    Allocator *allocator = Allocator::getInstance();
    return allocator->allocateFor(cbytes);
}

extern "C" void myfree(void *ptr){
    Allocator *allocator = Allocator::getInstance();
    allocator->freePtr(ptr);
}

...

That source file defines the functions to be used by C code, as well as methods of allocator.h which by itself includes other C++ stuff.

My C client file (cclient.c) is:

#include <stdio.h>
#include "mymalloc.h"

int main(void){
    void *p = mymalloc(500);
    printf("%p\n", p);
    return 0;
}

I was under the impression that since I have those wrapper functions at my top level and since their declarations can be viewed by C code everything should be ok but I am getting linking errors: (sample/example shown)

./libmymalloc.a(allocator.o): In function `Allocator::getInstance()':
allocator.cpp:(.text+0x3cf): undefined reference to `operator new(unsigned long)'
allocator.cpp:(.text+0x3fa): undefined reference to `operator delete(void*, unsigned long)'
./libmymalloc.a(allocator.o):(.data.DW.ref.__gxx_personality_v0[DW.ref.__gxx_personality_v0]+0x0): undefined reference to `__gxx_personality_v0'

The way I am compiling and linking, in favor of clarity, is

g++ -c allocator.cpp
... (same for the rest .cpp files)
gcc -c cclient.c
gcc cclient.o allocator.o ...(all other c++ objectives)...

Edit (After first three answers): I know that I can link using g++. I would be interested in how to link with the C compiler, so that someone having available only gcc and the objectives (or a library from those) could link on his own.

(This question could be a duplicate, but I have read all other questions in SO and I couldn't deduct what I was doing wrong.)