[protobuf] Re: Issue 469 in protobuf: how to write/read more than one piece of message to/from a text file in c++
Comment #6 on issue 469 by wuy...@gmail.com: how to write/read more than
one piece of message to/from a text file in c++
http://code.google.com/p/protobuf/issues/detail?id=469
As said by https://developers.google.com/protocol-buffers/docs/techniques,
the following code is passed to test.
Generally,it's a way that you yourself encode the string and decode it.
#include "GFileState.pb.h"
#include
#include
#include
using std::string;
using std::fstream;
using std::cout;
int main(int argc,char* argv[])
{
string fPath("message.txt");
string strMsg;
charbuf[1024] = {0};
fstream f;
int size;
f.open(fPath.c_str(),std::ios_base::app | std::ios_base::binary);
FileState msg,msg2;
msg.set_name("D:\\Test1");
msg.set_state(FILE_ACTION_ADD);
msg.SerializeToString(&strMsg);
//msg.SerializePartialToString(&strMsg);
size= strMsg.length();
f.write((char*)&size,sizeof(size));
f.write(strMsg.c_str(),size);
f.seekg(std::ios_base::end);
msg.set_name("/usr/home/nc/download");
msg.set_state(FILE_ACTION_MODIFY);
msg.SerializeToString(&strMsg);
size= strMsg.length();
f.write((char*)&size,sizeof(size));
f.write(strMsg.c_str(),size);
f.close();
f.open(fPath.c_str(),std::ios_base::in | std::ios_base::binary);
f.seekg(std::ios_base::beg);
strMsg.clear();
size = 0;
while(!f.eof())
{
f.read((char*)&size,sizeof(size));
if(size > 0 && size < sizeof(buf))
{
f.read(buf,size);
msg.ParseFromString(buf);
cout<<"name:\t\t"<(msg.state())<>strMsg;
return 0;
}
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[protobuf] Re: Issue 469 in protobuf: how to write/read more than one piece of message to/from a text file in c++
Comment #5 on issue 469 by wuy...@gmail.com: how to write/read more than
one piece of message to/from a text file in c++
http://code.google.com/p/protobuf/issues/detail?id=469
Yes,it is just binary data chunk. When I open the file stored some protobuf
messages, it seems like that the SerializeToString method forms a c++
string with '\n' as the last character. And when debugging, the first
character of the serielized string is '\n' whose ASCII code is 0x0A.
if you try parse it in this way,it will work: head a character '\n' at the
buffer that receive the parsed binary data chunk gotten from readline.the
c++ example code is like:
string fPath("message.txt");
string strMsg;
char buf[1024] = {0};
fstream f;
f.open(fPath.c_str(),std::ios_base::in | std::ios_base::binary);
f.seekg(std::ios_base::beg);
while(!f.eof())
{
buf[0] = '\n';
f.getline(buf+1,sizeof(buf) - sizeof(char));
string strTmp(buf);
if(!strTmp.empty())
{
msg.ParseFromString(buf);
//msg.ParsePartialFromString(strTmp);
cout<<"name:\t\t"<(msg.state())
[protobuf] Re: Issue 469 in protobuf: how to write/read more than one piece of message to/from a text file in c++
Comment #4 on issue 469 by wuy...@gmail.com: how to write/read more than one piece of message to/from a text file in c++ http://code.google.com/p/protobuf/issues/detail?id=469 Yes,it is just binary data chunk. When I open the file stored some protobuf messages, it seems like that the SerializeToString method forms a c++ string with a "\n" as the last character. And when debugging, the first character of the serielized string is '\n' whose ASCII code is 0x0A. if you try parse it in this way,it will work: head a character '\n' at the buffer that receive the parse binary data chunk gotten from readline. At most of the time, it will work, yet there is a problem: when it failed to parse, you can do nothing, readint its source code, it's a lot of work. And I have come across this problem. In other words, the parsing method by heading a character '\n' is unreliable or unstable. Any one have other Feasible way to read/write messages from/to a file? Thanks. -- You received this message because this project is configured to send all issue notifications to this address. You may adjust your notification preferences at: https://code.google.com/hosting/settings -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To unsubscribe from this group and stop receiving emails from it, send an email to protobuf+unsubscr...@googlegroups.com. To post to this group, send email to protobuf@googlegroups.com. Visit this group at http://groups.google.com/group/protobuf?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
[protobuf] Re: Issue 469 in protobuf: how to write/read more than one piece of message to/from a text file in c++
Updates: Status: Invalid Owner: xiaof...@google.com Comment #3 on issue 469 by xiaof...@google.com: how to write/read more than one piece of message to/from a text file in c++ http://code.google.com/p/protobuf/issues/detail?id=469 You must delimiter your messages by some other means rather than "lines". Reading "a line" from a binary file is almost always wrong. Serialized messages are just binary data chunks. You can use whatever means you use to read/write multiple data chunks in a file to read/write multiple messages. -- You received this message because this project is configured to send all issue notifications to this address. You may adjust your notification preferences at: https://code.google.com/hosting/settings -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To unsubscribe from this group and stop receiving emails from it, send an email to protobuf+unsubscr...@googlegroups.com. To post to this group, send email to protobuf@googlegroups.com. Visit this group at http://groups.google.com/group/protobuf?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
[protobuf] Re: Issue 469 in protobuf: how to write/read more than one piece of message to/from a text file in c++
Comment #2 on issue 469 by wuy...@gmail.com: how to write/read more than one piece of message to/from a text file in c++ http://code.google.com/p/protobuf/issues/detail?id=469 Noting this,https://developers.google.com/protocol-buffers/docs/cpptutorial?hl=zh-CN gives a example of read/write multiple message from/to a file, but a better way is to allow user to read/write message from/to file at any time. -- You received this message because this project is configured to send all issue notifications to this address. You may adjust your notification preferences at: https://code.google.com/hosting/settings -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To unsubscribe from this group and stop receiving emails from it, send an email to protobuf+unsubscr...@googlegroups.com. To post to this group, send email to protobuf@googlegroups.com. Visit this group at http://groups.google.com/group/protobuf?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
[protobuf] Re: Issue 469 in protobuf: how to write/read more than one piece of message to/from a text file in c++
Comment #1 on issue 469 by wuy...@gmail.com: how to write/read more than one piece of message to/from a text file in c++ http://code.google.com/p/protobuf/issues/detail?id=469 (No comment was entered for this change.) Attachments: mail.cpp 1.2 KB -- You received this message because this project is configured to send all issue notifications to this address. You may adjust your notification preferences at: https://code.google.com/hosting/settings -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. To unsubscribe from this group and stop receiving emails from it, send an email to protobuf+unsubscr...@googlegroups.com. To post to this group, send email to protobuf@googlegroups.com. Visit this group at http://groups.google.com/group/protobuf?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
