protobuf的C简单的代码例子（四）

构造  Repeated Submessages
构造一个 emessage.proto 文件

message Submessage

{

    required int32 value=1;

}

message EMessage

{

    repeated Submessage a=1;

}
下面给出打包代码：

#include<stdio.h>
#include<stdlib.h>
#include"dmessage.pb-c.h"

int main
(int argc,constchar*
argv[])
{
    Submessage**subs;
    void*buf;
    unsigned len;
    subs = malloc
(sizeof(Submessage*)*(argc-1));
    for(i
=1; i
< argc; i++)
      {
        subs[i-1]=
malloc (sizeof(Submessage));
        submessage__init (subs[i-1]);
        subs[i-1]->value
= atoi(argv[i]);
      }    
    msg.n_a
= argc-1;
    msg.a
= subs;
    len = emessage__get_packed_size
(&msg);// This is the calculated packing length
    buf = malloc
(len);                   
// Allocate memory
   emessage__pack (&msg, buf);
            // Pack msg, including submessages

    fprintf(stderr,"Writing %d serializedbytes\n",len);//
See the length of message
    fwrite (buf, len,1,
stdout);          
// Write to stdout to allow direct command line piping
   
    free(buf);// Free the allocated serialized buffer
   for(i
=1; i
< argc; i++)
     free (subs[i]);
   free (subs);
   return0;
}
值得注意的是重复域创建了两个域，n_a  submessagesd 的个数，另一个是submessages
自己。（理解这句话需要阅读.proto文件生成的源代码）

下面给出解包的源代码
#include <stdio.h>
#include"emessage.pb-c.h"
#define MAX_MSG_SIZE
4096

int main
(int argc,constchar*
argv[])
{
    EMessage*msg;
    char c;int i=0;
    uint8_tbuf[MAX_MSG_SIZE];// Input data container for bytes
   
    while(fread(&c,1,1,stdin)!=0)
    {
       if(i
>= MAX_MSG_SIZE)
       {
           fprintf(stderr,"message too long for allocatedbuffer\n");
           return1;
       }
       buf[i++]= c;
    }
   
    msg = emessage__unpack(NULL,i,buf);//
Deserialize the serialized input
    if(msg
== NULL)
    {
       fprintf(stderr,"error unpacking incomingmessage\n");
       return1;
    }
    for(i
=0; i
< msg->n_a; i++)
      printf ("%d\n", msg->a[i]->value);
   
   emessage__free_unpacked(msg,NULL);
   
    return0;
}
命令行运行：
./emessage_serialize
45|./emessage_deserialize

Writing:8 serialized bytes
4
5
./emessage_serialize
458|./emessage_deserialize

4
5
8