49. 有如下程序：
#include <iostream>
using namespace std;
class Stack
{
public:
Stack(unsigned n=10):size(n){rep_=new int[size];top=0;}
Stack(Stack&s):size(s.size)
{
rep_ =new int[size];
for(unsigned i=0;i<s.top;i++)rep_[i]=s.rep_[i];
top=s.top;
}
~Stack(){delete []rep_;}
void push(int a){rep_[top]=a;top++;}
int pop(){--top;return rep_[top];}
bool isEmpty()const{return top==0;}
private:
int *rep_;
unsigned size,top;
};
int main()
{
Stack s1;
for(int i=1;i<5;i++)s1.push(i);
Stack s2(s1);
for(int i=1;i<3;i++)cout<<s2.pop()<<',';
s2.push(6);
s1.push(7);
while(!s2.isEmpty())cout<<s2.pop()<<',';
return 0;
}
执行上面程序的输出是______。
