/in/foo.cc: In function 'double sub(std::__cxx11::string, double)':
/in/foo.cc:27:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  while(i<s.size())
        ~^~~~~~~~~
/in/foo.cc:49:24: warning: array subscript has type 'char' [-Wchar-subscripts]
    if(s[i]=='('||f[s[i]]>f[ch[ch_]])
                        ^
/in/foo.cc:56:7: warning: operation on 'd_' may be undefined [-Wsequence-point]
     d[--d_]=cal(d[d_],ch[ch_--],d[d_+1]);
       ^~~~
/in/foo.cc:56:7: warning: operation on 'd_' may be undefined [-Wsequence-point]
/in/foo.cc: In function 'double cal(double, char, double)':
/in/foo.cc:20:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^