Floating-point precision conversion error

[ApacheWang]

What is the issue you have?

Please describe the steps to reproduce the issue.

1. pls use this case to reproduce.
   std::string tmp = "{\n" " \"compareType\":0,\n" " \"feature\":100,\n" " \"id\":8,\n" " \"leftNodeID\":17,\n" " \"rightNodeID\":18,\n" " \"threshold\":[\n" " 0.2709993869\n" " ]\n" " }"; json js = json::parse(tmp); cout << js.dump() << endl;
2. And the threshold change to 0.27099938690000003

Can you provide a small but working code example?

What is the expected behavior?

And what is the actual behavior instead?

Which compiler and operating system are you using?

• Compiler: ___
• Operating system: ___

Which version of the library did you use?

• latest release version 3.9.1
• other release - please state the version: ___
• the develop branch

If you experience a compilation error: can you compile and run the unit tests?

• yes
• no - please copy/paste the error message below