限定修饰符说明

repeated 代表可重复，我们可以理解为数组：

syntax = "proto3";//指定版本信息，不指定会报错message Person //message为关键字，作用为定义一种消息类型
{string name = 1;    //姓名int32 id = 2;       //idstring email = 3;   //邮件
}message AddressBook
{repeated Person people = 1;
}

字段API

而对于字段修饰符为repeated的字段生成的函数，则稍微有一些不同，如people字段，则编译器会为其产生如下的代码：

int people_size() const;
void clear_people();
const ::Person& people(int index) const;
::Person* mutable_people(int index);
::Person* add_people();
::google::protobuf::RepeatedPtrField< ::Person >* mutable_people();
const ::google::protobuf::RepeatedPtrField< ::Person >& people() const;

测试程序

void set_addressbook()
{AddressBook obj;Person *p1 = obj.add_people(); //新增加一个Personp1->set_name("mike");p1->set_id(1);p1->set_email("mike@qq.com");Person *p2 = obj.add_people(); //新增加一个Personp2->set_name("jiang");p2->set_id(2);p2->set_email("jiang@qq.com");Person *p3 = obj.add_people(); //新增加一个Personp3->set_name("abc");p3->set_id(3);p3->set_email("abc@qq.com");fstream output("pb.xxx", ios::out | ios::trunc | ios::binary);bool flag = obj.SerializeToOstream(&output);//序列化if (!flag){cerr << "Failed to write file." << endl;return;}output.close();//关闭文件
}void get_addressbook()
{AddressBook obj;fstream input("./pb.xxx", ios::in | ios::binary);obj.ParseFromIstream(&input);  //反序列化input.close(); //关闭文件for (int i = 0; i < obj.people_size(); i++){const Person& person = obj.people(i);//取第i个peoplecout << "第" << i + 1 << "个信息\n";cout << "name = " << person.name() << endl;cout << "id = " << person.id() << endl;cout << "email = " << person.email() << endl << endl;}
}