问题描述

I'm new to C++ programming, but have been working in C and Java for a long time. I'm trying to do an interface-like hierarchy in some serial protocol I'm working on, and keep getting the error:

Undefined reference to 'operator delete(void*)'

The (simplified) code follows below:

PacketWriter.h:

class PacketWriter {
public:
    virtual ~PacketWriter() {}
    virtual uint8_t nextByte() = 0;
}

StringWriter.h:

class StringWriter : public PacketWriter {
public:
    StringWriter(const char* message);
    virtual uint8_t nextByte();
}

The constructor and nextByte functions are implemented in StringWriter.cpp, but nothing else. I need to be able to delete a StringWriter from a pointer to a PacketWriter, and i've been getting various other similar errors if I define a destructor for StringWriter, virtual or not. I'm sure it's a simple issue that I'm overlooking as a newbie.

Also, I'm writing this for an AVR chip, using avr-g++ on Windows.

Thanks

If you are not linking against the standard library for some reason (as may well be the case in an embedded scenario), you have to provide your own operators new and delete. In the simplest case, you could simply wrap malloc, or allocate memory from your own favourite source:

void * operator new(std::size_t n)
{
  void * const p = std::malloc(n);
  // handle p == 0
  return p;
}

void operator delete(void * p) // or delete(void *, std::size_t)
{
  std::free(p);
}

You should never have to do this if you are compiling for an ordinary, hosted platform, so if you do need to do this, you better be familiar with the intricacies of memory management on your platform.

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