/in/foo.cc: In function 'double sub(std::__cxx11::string, double)':
/in/foo.cc:28:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     while(i<s.size())
           ~^~~~~~~~~
/in/foo.cc:50:33: warning: array subscript has type 'char' [-Wchar-subscripts]
             if(s[i]=='('||f[s[i]]>f[ch[ch_]])
                                 ^
/in/foo.cc:57:19: warning: operation on 'd_' may be undefined [-Wsequence-point]
                 d[--d_]=cal(d[d_],ch[ch_--],d[d_+1]);
                   ^~~~
/in/foo.cc:57:19: warning: operation on 'd_' may be undefined [-Wsequence-point]
/in/foo.cc: In function 'double cal(double, char, double)':
/in/foo.cc:21:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^