c++ - 运算符删除导致堆损坏，而运算符新工作正常

Question

我已经让 operator new 工作了，但是当我调用 delete 时，它​​在 free (ptr) 行崩溃了。任何人都可以告诉我在这个基类中重载 operator new 和 delete 时我做错了什么吗？提示:我不是在问设计问题。

class Base {
private: 
    int i;

public:  
    Base () : i (10) {
    }

    static void * operator new (size_t size) {  
       if (size = 0) size = 1;  // please read this line carefully! size = 0!
       return malloc (size);  
    }

    static void operator delete (void *ptr, size_t size) {
       if (ptr == NULL) return;
       free (ptr);
    }
};

Answer 1

这对我有用:

#include <cstdlib>
using namespace std;
class Base {
public:
    void * operator new(size_t size) {
       if (size == 0) size = 1;
       return malloc (size);
    }

    void operator delete (void *ptr, size_t size) {
       if (ptr == NULL) return;
       free (ptr);
    }
};

int main()
{
    Base* b = new Base;
    delete b;
    return 0;
}

---

hank@tardis:/tmp$ g++ -o test test.cpp 
hank@tardis:/tmp$ ./test 
hank@tardis:/tmp$ valgrind ./test 
==7229== HEAP SUMMARY:
==7229==     in use at exit: 0 bytes in 0 blocks
==7229==   total heap usage: 1 allocs, 1 frees, 1 bytes allocated
==7229== 
==7229== All heap blocks were freed -- no leaks are possible
==7229== 
==7229== For counts of detected and suppressed errors, rerun with: -v
==7229== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 4 from 4)