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Posted to dev@avro.apache.org by "Paul Jacobs (JIRA)" <ji...@apache.org> on 2012/12/07 21:41:21 UTC
[jira] [Created] (AVRO-1216) Setting precision for the output
stream
Paul Jacobs created AVRO-1216:
---------------------------------
Summary: Setting precision for the output stream
Key: AVRO-1216
URL: https://issues.apache.org/jira/browse/AVRO-1216
Project: Avro
Issue Type: Bug
Components: c++
Affects Versions: 1.7.2
Environment: Linux x86_64
Reporter: Paul Jacobs
Priority: Minor
Attachments: cpx.json, precision.cpp
There's no way, that I know of, to set the precision level on the output stream.
I want to take an avro object, with double fields, and json encode it into a string. However, when I do this the encoded doubles have lost precision. I suspect this is because the precision I set on the ostringstream and resulting avro::ostreamOutputStream isn't working.
Here's an example inspired by the tutorial (http://avro.apache.org/docs/1.7.2/api/cpp/html/index.html). Using their cpx.json
00001 {
00002 "type": "record",
00003 "name": "cpx",
00004 "fields" : [
00005 {"name": "re", "type": "double"},
00006 {"name": "im", "type" : "double"}
00007 ]
00008 }
Generating cpx.hh by
avrogencpp -i cpx.json -o cpx.hh -n c
The test program is then:
1#include "cpx.hh"
2#include "avro/Compiler.hh"
3#include "avro/Encoder.hh"
4#include "avro/Decoder.hh"
5#include "avro/Specific.hh"
6#include "avro/Generic.hh"
7#include <sstream>
8#include <fstream>
9
10using namespace std;
11int main()
12{
13 ifstream ifs("cpx.json");
14 avro::ValidSchema type_schema;
15 avro::compileJsonSchema(ifs, type_schema);
16
17 ostringstream oss (ostringstream::out);
18 oss.precision(30); // doesn't matter
19 std::auto_ptr<avro::OutputStream> out = avro::ostreamOutputStream(oss);
20 avro::EncoderPtr e = avro::jsonEncoder(type_schema);
21 e->init(*out);
22 c::cpx complex;
23 complex.re = 1.123456789;
24 complex.im = 2.01;
25 avro::encode(*e, complex);
26 e->flush();
27 cout.precision(30);
28 cout << oss.str() << endl;
29
30 return 0;
31}
If we then compile and run this we get:
{"re":1.12346,"im":2.01}
Where as I'd expect something like:
{"re":1.12346789,"im":2.01}
It doesn't seem to matter where/if we set the precision on the output stream (line 18).
Is there a different way to handle this? How do I keep the precision from getting stripped off double when doing json encoding?
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