GitHub user mygityf opened a pull request: https://github.com/apache/thrift/pull/870
THRIFT-3636 The precision is 15 bits after dot of casting from double to string in Thrift-cpp-library- json-protocol. Cpp json protocol double precision should be 16 bits You can merge this pull request into a Git repository by running: $ git pull https://github.com/mygityf/thrift cpp-json-protocol-double-precision-should-be-16bits Alternatively you can review and apply these changes as the patch at: https://github.com/apache/thrift/pull/870.patch To close this pull request, make a commit to your master/trunk branch with (at least) the following in the commit message: This closes #870 ---- commit 93f0c9836dbcbb9564413c3f4a20e85799cafb7d Author: Wang Yaofu <voip...@sina.cn> Date: 2016-02-15T02:43:09Z THRIFT-3636 The precision is 15 bits after dot of casting from double to string in Thrift-cpp-library- json-protocol. The precision is 15 bits after dot of format casting from double to string in Thrift-cpp-library- json-protocol. But the expected precision is 16 bits after dot in Thrift-json-protocol. The solution: To Change code 'str.precision(std::numeric_limits<double>::digits10 + 1);' to 'str.precision(std::numeric_limits<double>::digits10 + 2);' in function doubeToString file TJSONProtocol.cpp at line 524, e.g: before: In C++ TJSONProtocol.cpp: double a = 1.12345678906666663; string astr = doubleToString(a); double b = stringToDouble(astr); the result as below: a = 1.1234567890666667 astr = "1.123456789066667" b = 1.1234567890666669 after changing: the result as below: a = 1.1234567890666667 astr = "1.1234567890666667" b = 1.1234567890666667 This result is expected. commit e0bebd14f9df02d31603506b72eb5dbcfea74ce6 Author: Wang Yaofu <voip...@sina.cn> Date: 2016-02-15T02:46:48Z THRIFT-3636 The precision is 15 bits after dot of casting from double to string in Thrift-cpp-library- json-protocol. The precision is 15 bits after dot of format casting from double to string in Thrift-cpp-library- json-protocol. But the expected precision is 16 bits after dot in Thrift-json-protocol. The solution: To Change code 'str.precision(std::numeric_limits<double>::digits10 + 1);' to 'str.precision(std::numeric_limits<double>::digits10 + 2);' in function doubeToString file TJSONProtocol.cpp at line 524, e.g: before: In C++ TJsonProtocol.cpp: double a = 1.12345678906666663; string astr = doubleToString(a); double b = stringToDouble(astr); the result as below: a = 1.1234567890666667 astr = "1.123456789066667" b = 1.1234567890666669 after changing: the result as below: a = 1.1234567890666667 astr = "1.1234567890666667" b = 1.1234567890666667 This result is expected. ---- --- If your project is set up for it, you can reply to this email and have your reply appear on GitHub as well. If your project does not have this feature enabled and wishes so, or if the feature is enabled but not working, please contact infrastructure at infrastruct...@apache.org or file a JIRA ticket with INFRA. ---