请指出下列代表有几处错误？
#include <stdio.h>
class A
{
public:
virtual void f(){}
public:
A()
{
f();
}
};
class B1:public A()
{
private:
char *_s;
public:
B1()
{
_s=new char[1024];
}
private:
void f()
{
delete _s[];
_s=NULL;
}
}
class B2:public A
{
private:
int * _m;
public:
B2()
{
_m=new int(2016);
}
private:
virtual void f()
{
delete _m;
_m=NULL;
}
}
int main()
{
A *a1=new B();
A *a2=new C;
delete a1;
delete a2;
return 0;
} 
