multiline text values

[ins2718]

std::string s = "{\"text\":\"line 1\nline 2\"}";
auto json = nlohmann::json::parse(s);

This json-object causes an error. Standard facilities python, php and js correctly handle it.

[nlohmann]

Newline characters must be escaped, see RFC 7159, Section 7:

All Unicode characters may be placed within the quotation marks, except for the characters that must be escaped: quotation mark, reverse solidus, and the control characters (U+0000 through U+001F).

As \n is U+000A, it must be escaped. In your example, std::string s = "{\"text\":\"line 1\\nline 2\"}"; would be correct.

[nlohmann]

(Side remark: Python fails to parse the string:

Python 2.7.11 (default, Mar  6 2016, 18:11:07) 
[GCC 4.2.1 Compatible Apple LLVM 7.3.0 (clang-703.0.21)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> s = "{\"text\":\"line 1\nline 2\"}"
>>> s
'{"text":"line 1\nline 2"}'
>>> print s
{"text":"line 1
line 2"}
>>> import json
>>> json.loads(s)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/homebrew/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 339, in loads
    return _default_decoder.decode(s)
  File "/usr/local/homebrew/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 364, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/local/homebrew/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 380, in raw_decode
    obj, end = self.scan_once(s, idx)
ValueError: Invalid control character at: line 1 column 16 (char 15)

[ins2718]

Thank you! Standard php-function "json_encode" not escaping new lines, so I thought it was the correct json-object. In python 3.5.1 is no exception.

[nlohmann]

For Python 3.5.1, I get the same error:

Python 3.5.1 (default, Dec  8 2015, 17:46:37) 
[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.1.76)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> s = "{\"text\":\"line 1\nline 2\"}"
>>> s
'{"text":"line 1\nline 2"}'
>>> print(s)
{"text":"line 1
line 2"}
>>> import json
>>> json.loads(s)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/homebrew/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/json/__init__.py", line 319, in loads
    return _default_decoder.decode(s)
  File "/usr/local/homebrew/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/json/decoder.py", line 339, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/local/homebrew/Cellar/python3/3.5.1/Frameworks/Python.framework/Versions/3.5/lib/python3.5/json/decoder.py", line 355, in raw_decode
    obj, end = self.scan_once(s, idx)
json.decoder.JSONDecodeError: Invalid control character at: line 1 column 16 (char 15)

But you are right for PHP's json_encode - strange that this function is not compliant to the JSON spec.