transfer.cpp: In function 'std::vector<int> get_attachment(std::vector<int>)':
transfer.cpp:16:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
16 | for(int i=0;i<source.size();i++)if(source[i] == 1)ans ^= i;
| ~^~~~~~~~~~~~~~
transfer.cpp:31:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
31 | for(int i=n;i<source.size();i++)kk ^= source[i];
| ~^~~~~~~~~~~~~~
transfer.cpp: In function 'std::vector<int> retrieve(std::vector<int>)':
transfer.cpp:44:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
44 | for(int i=n;i<data.size()-1;i++)temp ^= data[i];
| ~^~~~~~~~~~~~~~
transfer.cpp:88:1: warning: control reaches end of non-void function [-Wreturn-type]
88 | }
| ^
transfer.cpp:45:2: warning: 'temp' may be used uninitialized in this function [-Wmaybe-uninitialized]
45 | if(temp == data[data.size()-1]) // the part of ans1 has been changed.
| ^~