C++工程，protobuf初识，读prototxt文件，下载安装，消息结构体详解，编译命令

1，下载安装包

https://github.com/protocolbuffers/protobuf/releases/latest

For example: if you only need C++, download `protobuf-cpp-[VERSION].tar.gz`; if
you need C++ and Java, download `protobuf-java-[VERSION].tar.gz` (every package
contains C++ source already); if you need C++ and multiple other languages,
download `protobuf-all-[VERSION].tar.gz`.

2，解压安装

$ tar -vxf protobuf-cpp-3.8.0.tar.gz
$ cd protobuf-3.8.0/ 
$ ./configure
$ make
$ make check
$ sudo make install
$ sudo ldconfig # refresh shared library cache.

2.1，查看版本

$ protoc --version

3，使用

https://www.jianshu.com/p/419efe983cb2

枚举类为什么有０
https://blog.youkuaiyun.com/skh2015java/article/details/78404235

https://blog.youkuaiyun.com/hry2015/article/details/70766603

https://www.cnblogs.com/zhouyang209117/p/7218719.html

https://blog.youkuaiyun.com/yang332233/article/details/83657735

3.1，定义数据结构体－－－编写config.proto

// 指定版本号为proto3; 否则默认使用proto2
// 注意：版本号指定必须放在第一行
syntax = "proto3";

// 包名，用来防止Protocol Buffers name space里的名字冲突 
package config