/in/foo.cc:37:26: warning: multi-character character constant [-Wmultichar]
             if(stack[i]=='】'&& f_stack[top]!='【')
                          ^~~~~
/in/foo.cc:37:48: warning: multi-character character constant [-Wmultichar]
             if(stack[i]=='】'&& f_stack[top]!='【')
                                                ^~~~~
/in/foo.cc:39:26: warning: multi-character character constant [-Wmultichar]
             if(stack[i]=='》'&& f_stack[top]!='《')
                          ^~~~~
/in/foo.cc:39:48: warning: multi-character character constant [-Wmultichar]
             if(stack[i]=='》'&& f_stack[top]!='《')
                                                ^~~~~
/in/foo.cc:41:26: warning: multi-character character constant [-Wmultichar]
             if(stack[i]=='）'&& f_stack[top]!='（')
                          ^~~~~
/in/foo.cc:41:48: warning: multi-character character constant [-Wmultichar]
             if(stack[i]=='）'&& f_stack[top]!='（')
                                                ^~~~~
/in/foo.cc: In function 'void finds()':
/in/foo.cc:11:17: error: reference to 'next' is ambiguous
     len=mid=top=next=0;
                 ^~~~
/in/foo.cc:7:19: note: candidates are: int next
 int n,len,mid,top,next;//n，长度，中位数，栈底（这次就不用字符赋值判0来骗分了） 
                   ^~~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:66:0,
                 from /usr/include/c++/6/bits/char_traits.h:39,
                 from /usr/include/c++/6/ios:40,
                 from /usr/include/c++/6/ostream:38,
                 from /usr/include/c++/6/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_iterator_base_funcs.h:205:5: note:                 template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
     next(_ForwardIterator __x, typename
     ^~~~