foo.cpp: In function 'int main()':
foo.cpp:26:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<num1.size();++i)
                 ~^~~~~~~~~~~~
foo.cpp:28:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=0;j<num2.size();++j)
                     ~^~~~~~~~~~~~
foo.cpp:36:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int item=0;item<v_sum.size()-1;++item)
                            ~~~~^~~~~~~~~~~~~~~
foo.cpp:50:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int item=i,k=0;k<v_temp.size();++k,++item)
                                ~^~~~~~~~~~~~~~
foo.cpp:55:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 if(item==v_sum.size()-1)
                    ~~~~^~~~~~~~~~~~~~~~