Unable to parse numbers if std::locale() changes the decimal

[DosMike]

Describe the bug
Hi, I'm not living in an English speaking country and as such I naturally set std::locale("") to make cpp use familiar number representations instead (This changes the decimal from a dot to a comma). There seems to be a problem where jsoncpp uses a string stream to parse decimals, and the input stream correctly uses the default locale set before, but this now differs from the locale required by Json.

To Reproduce
Steps to reproduce the behavior:

1. std::locale::global(std::locale("de_DE.UTF-8"));
2. jsonReader.parse("[123.45]", root, false);

Expected behavior
Should parse the number with dot as decimal without any issue.

Desktop (please complete the following information):

• OS: Linux
• Meson N/A
• Ninja N/A

Additional context
The solution is to imbue the streams with the local required by json like is.imbue(std::local("en_US.UTF-8")) for the reader:

jsoncpp/src/lib_json/json_reader.cpp

Line 590 in 89e2973

IStringStream is(String(token.start_, token.end_));

jsoncpp/src/lib_json/json_reader.cpp

Line 1624 in 89e2973

IStringStream is(String(token.start_, token.end_));

Don't currently know if the writer is affected with sprintf:

jsoncpp/src/lib_json/json_writer.cpp

Line 127 in 89e2973

String valueToString(double value, bool useSpecialFloats,

Workaround is to temporarily set the locale to en_US manually