/in/foo.cc: In function 'double string2double(std::__cxx11::string)':
/in/foo.cc:35:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0 ; i < t.length() ; i++)
                     ~~^~~~~~~~~~~~
/in/foo.cc: In function 'int isop(int)':
/in/foo.cc:56:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0 ; i < sign.size() ; i++)
                     ~~^~~~~~~~~~~~~
/in/foo.cc: In function 'double work(std::__cxx11::string)':
/in/foo.cc:157:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0 ; i < expr.length() ; i++)
                     ~~^~~~~~~~~~~~~~~
/in/foo.cc:160:66: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         while(isop(expr[i])==-1&&expr[i]!='('&&expr[i]!=')' && i < expr.length())
                                                                ~~^~~~~~~~~~~~~~~
/in/foo.cc: In function 'int main(int, const char**)':
/in/foo.cc:193:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int l = 0 ; l < ori.size() ; l++)
                     ~~^~~~~~~~~~~~
/in/foo.cc:202:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int l = 0 ; l < allexp[i].size() ; l++)
                         ~~^~~~~~~~~~~~~~~~~~
/in/foo.cc:207:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0 ; i < test.size() ; i++){
                     ~~^~~~~~~~~~~~~
/in/foo.cc:211:20: warning: unused variable 'nowout' [-Wunused-variable]
             double nowout = work(allexp[k]);
                    ^~~~~~