{

Test test;

test.add_id(10);

test.add_id(20);

test.add_id(30);

std::cout<<test.id_size()<<std::endl;

std::cout<<test.id(1)<<std::endl;

const RepeatedField<int64>& id_vec = test.id();

for(auto a : id_vec)

{

// *itr += 1000; // this will throw an compiler error. It is not mutable.

std::cout<< "id: "<<a<<std::endl;

}

std::string str;

google::protobuf::TextFormat::PrintToString(test, &str);

std::cout<< str << std::endl;

RepeatedField<int64>* mut_vec = test.mutable_id();

for(auto itr = mut_vec->begin(); itr != mut_vec->end(); ++itr)

{

*itr += 1000; // this will throw an compiler error. It is not mutable.

std::cout<< "id: "<<*itr<<std::endl;

}

std::string str2;

google::protobuf::TextFormat::PrintToString(test, &str2);

std::cout<< str2 << std::endl;