README.md 21.8 KB
Newer Older
Niels's avatar
cleanup    
Niels committed
1
![JSON for Modern C++](https://raw.githubusercontent.com/nlohmann/json/master/doc/json.gif)
Niels's avatar
Niels committed
2

Niels's avatar
Niels committed
3
[![Build Status](https://travis-ci.org/nlohmann/json.svg?branch=master)](https://travis-ci.org/nlohmann/json)
Niels's avatar
cleanup    
Niels committed
4
[![Build Status](https://ci.appveyor.com/api/projects/status/1acb366xfyg3qybk?svg=true)](https://ci.appveyor.com/project/nlohmann/json)
Niels's avatar
Niels committed
5
[![Coverage Status](https://img.shields.io/coveralls/nlohmann/json.svg)](https://coveralls.io/r/nlohmann/json)
Niels's avatar
cleanup    
Niels committed
6
[![Coverity Scan Build Status](https://scan.coverity.com/projects/5550/badge.svg)](https://scan.coverity.com/projects/nlohmann-json)
Niels's avatar
Niels committed
7
[![Try online](https://img.shields.io/badge/try-online-blue.svg)](http://melpon.org/wandbox/permlink/wuiuqYiYqRTdI3rG)
Niels's avatar
Niels committed
8
[![Documentation](https://img.shields.io/badge/docs-doxygen-blue.svg)](http://nlohmann.github.io/json)
Niels's avatar
Niels committed
9
[![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/nlohmann/json/master/LICENSE.MIT)
Niels's avatar
Niels committed
10
[![Github Releases](https://img.shields.io/github/release/nlohmann/json.svg)](https://github.com/nlohmann/json/releases)
Niels's avatar
Niels committed
11
12
13
14
15
16
17
18
19
20
[![Github Issues](https://img.shields.io/github/issues/nlohmann/json.svg)](http://github.com/nlohmann/json/issues)

## Design goals

There are myriads of [JSON](http://json.org) libraries out there, and each may even have its reason to exist. Our class had these design goals:

- **Intuitive syntax**. In languages such as Python, JSON feels like a first class data type. We used all the operator magic of modern C++ to achieve the same feeling in your code. Check out the [examples below](#examples) and you know, what I mean.

- **Trivial integration**. Our whole code consists of a single header file `json.hpp`. That's it. No library, no subproject, no dependencies, no complex build system. The class is written in vanilla C++11. All in all, everything should require no adjustment of your compiler flags or project settings.

21
- **Serious testing**. Our class is heavily [unit-tested](https://github.com/nlohmann/json/blob/master/test/src/unit.cpp) and covers [100%](https://coveralls.io/r/nlohmann/json) of the code, including all exceptional behavior. Furthermore, we checked with [Valgrind](http://valgrind.org) that there are no memory leaks.
Niels's avatar
Niels committed
22
23
24

Other aspects were not so important to us:

Niels's avatar
Niels committed
25
- **Memory efficiency**. Each JSON object has an overhead of one pointer (the maximal size of a union) and one enumeration element (1 byte). The default generalization uses the following C++ data types: `std::string` for strings, `int64_t`, `uint64_t` or `double` for numbers, `std::map` for objects, `std::vector` for arrays, and `bool` for Booleans. However, you can template the generalized class `basic_json` to your needs.
Niels's avatar
Niels committed
26
27
28

- **Speed**. We currently implement the parser as naive [recursive descent parser](http://en.wikipedia.org/wiki/Recursive_descent_parser) with hand coded string handling. It is fast enough, but a [LALR-parser](http://en.wikipedia.org/wiki/LALR_parser) with a decent regular expression processor should be even faster (but would consist of more files which makes the integration harder).

Niels's avatar
cleanup    
Niels committed
29
See the [contribution guidelines](https://github.com/nlohmann/json/blob/master/.github/CONTRIBUTING.md#please-dont) for more information.
Niels's avatar
Niels committed
30

Niels's avatar
Niels committed
31
32
## Integration

Niels's avatar
Niels committed
33
The single required source, file `json.hpp` is in the `src` directory or [released here](https://github.com/nlohmann/json/releases). All you need to do is add
Niels's avatar
Niels committed
34
35
36
37
38
39
40
41
42
43

```cpp
#include "json.hpp"

// for convenience
using json = nlohmann::json;
```

to the files you want to use JSON objects. That's it. Do not forget to set the necessary switches to enable C++11 (e.g., `-std=c++11` for GCC and Clang).

44
:beer: If you are using OS X and [Homebrew](http://brew.sh), just type `brew tap nlohmann/json` and `brew install nlohmann_json` and you're set. If you want the bleeding edge rather than the latest release, use `brew install nlohmann_json --HEAD`.
Niels's avatar
Niels committed
45

46
47
## Supported compilers

Niels's avatar
Niels committed
48
Though it's 2016 already, the support for C++11 is still a bit sparse. Currently, the following compilers are known to work:
49

Niels's avatar
Niels committed
50
- GCC 4.9 - 6.0 (and possibly later)
Niels's avatar
Niels committed
51
- Clang 3.4 - 3.9 (and possibly later)
Niels's avatar
Niels committed
52
- Microsoft Visual C++ 2015 / 14.0 (and possibly later)
Niels's avatar
Niels committed
53

54
55
I would be happy to learn about other compilers/versions.

Niels's avatar
Niels committed
56
Please note:
Niels's avatar
Niels committed
57

Niels's avatar
Niels committed
58
- GCC 4.8 does not work because of two bugs ([55817](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55817) and [57824](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57824)) in the C++11 support. Note there is a [pull request](https://github.com/nlohmann/json/pull/212) to fix some of the issues.
59
60
- Android defaults to using very old compilers and C++ libraries. To fix this, add the following to your `Application.mk`. This will switch to the LLVM C++ library, the Clang compiler, and enable C++11 and other features disabled by default.
 
Niels's avatar
Niels committed
61
62
63
64
65
    ```
    APP_STL := c++_shared
    NDK_TOOLCHAIN_VERSION := clang3.6
    APP_CPPFLAGS += -frtti -fexceptions
    ```
66
 
67
68
69
    The code compiles successfully with [Android NDK](https://developer.android.com/ndk/index.html?hl=ml), Revision 9 - 11 (and possibly later) and [CrystaX's Android NDK](https://www.crystax.net/en/android/ndk) version 10.

- For GCC running on MinGW or Android SDK, the error `'to_string' is not a member of 'std'` (or similarly, for `strtod`) may occur. Note this is not an issue with the code,  but rather with the compiler itself. On Android, see above to build with a newer environment.  For MinGW, please refer to [this site](http://tehsausage.com/mingw-to-string) and [this discussion](https://github.com/nlohmann/json/issues/136) for information on how to fix this bug. For Android NDK using `APP_STL := gnustl_static`, please refer to [this discussion](https://github.com/nlohmann/json/issues/219).
Niels's avatar
Niels committed
70

71
72
73
74
The following compilers are currently used in [continuous integration](https://travis-ci.org/nlohmann/json):

| Compiler        | Operating System             | Version String |
|-----------------|------------------------------|----------------|
75
76
| GCC 4.9.3       | Ubuntu 14.04.4 LTS           | g++-4.9 (Ubuntu 4.9.3-8ubuntu2~14.04) 4.9.3 |
| GCC 5.3.0       | Ubuntu 14.04.4 LTS           | g++-5 (Ubuntu 5.3.0-3ubuntu1~14.04) 5.3.0 20151204 |
Niels's avatar
Niels committed
77
| GCC 6.1.1       | Ubuntu 14.04.4 LTS           | g++-6 (Ubuntu 6.1.1-3ubuntu11~14.04.1) 6.1.1 20160511 |
78
| Clang 3.8.0     | Ubuntu 14.04.4 LTS           | clang version 3.8.0 (tags/RELEASE_380/final) |
Niels's avatar
Niels committed
79
80
81
82
83
84
| Clang Xcode 6.1 | Darwin Kernel Version 13.4.0 (OSX 10.9.5) | Apple LLVM version 6.0 (clang-600.0.54) (based on LLVM 3.5svn) |
| Clang Xcode 6.2 | Darwin Kernel Version 13.4.0 (OSX 10.9.5) | Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn) |
| Clang Xcode 6.3 | Darwin Kernel Version 14.3.0 (OSX 10.10.3) | Apple LLVM version 6.1.0 (clang-602.0.49) (based on LLVM 3.6.0svn) |
| Clang Xcode 6.4 | Darwin Kernel Version 14.3.0 (OSX 10.10.3) | Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn) |
| Clang Xcode 7.1 | Darwin Kernel Version 14.5.0 (OSX 10.10.5) | Apple LLVM version 7.0.0 (clang-700.1.76) |
| Clang Xcode 7.2 | Darwin Kernel Version 15.0.0 (OSX 10.10.5) | Apple LLVM version 7.0.2 (clang-700.1.81) |
Niels's avatar
Niels committed
85
| Clang Xcode 7.3 | Darwin Kernel Version 15.0.0 (OSX 10.10.5) | Apple LLVM version 7.3.0 (clang-703.0.29) |
86
| Clang Xcode 8.0 | Darwin Kernel Version 15.5.0 (OSX 10.11.5) | Apple LLVM version 8.0.0 (clang-800.0.24.1) |
Niels's avatar
Niels committed
87
| Visual Studio 14 2015 | Windows Server 2012 R2 (x64) | Microsoft (R) Build Engine version 14.0.25123.0 | 
88

Niels's avatar
Niels committed
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
## Examples

Here are some examples to give you an idea how to use the class.

Assume you want to create the JSON object

```json
{
  "pi": 3.141,
  "happy": true,
  "name": "Niels",
  "nothing": null,
  "answer": {
    "everything": 42
  },
  "list": [1, 0, 2],
  "object": {
    "currency": "USD",
    "value": 42.99
  }
}
```

With the JSON class, you could write:

```cpp
// create an empty structure (null)
json j;

// add a number that is stored as double (note the implicit conversion of j to an object)
j["pi"] = 3.141;

// add a Boolean that is stored as bool
j["happy"] = true;

// add a string that is stored as std::string
j["name"] = "Niels";

// add another null object by passing nullptr
j["nothing"] = nullptr;

// add an object inside the object
j["answer"]["everything"] = 42;

// add an array that is stored as std::vector (using an initializer list)
j["list"] = { 1, 0, 2 };

// add another object (using an initializer list of pairs)
j["object"] = { {"currency", "USD"}, {"value", 42.99} };

// instead, you could also write (which looks very similar to the JSON above)
json j2 = {
  {"pi", 3.141},
  {"happy", true},
  {"name", "Niels"},
  {"nothing", nullptr},
  {"answer", {
    {"everything", 42}
  }},
  {"list", {1, 0, 2}},
  {"object", {
    {"currency", "USD"},
    {"value", 42.99}
  }}
};
```

AQNOUCH Mohammed's avatar
AQNOUCH Mohammed committed
156
Note that in all these cases, you never need to "tell" the compiler which JSON value you want to use. If you want to be explicit or express some edge cases, the functions `json::array` and `json::object` will help:
Niels's avatar
Niels committed
157
158

```cpp
Niels's avatar
Niels committed
159
// a way to express the empty array []
Niels's avatar
Niels committed
160
161
json empty_array_explicit = json::array();

Niels's avatar
Niels committed
162
163
// ways to express the empty object {}
json empty_object_implicit = json({});
Niels's avatar
Niels committed
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
json empty_object_explicit = json::object();

// a way to express an _array_ of key/value pairs [["currency", "USD"], ["value", 42.99]]
json array_not_object = { json::array({"currency", "USD"}), json::array({"value", 42.99}) };
```

### Serialization / Deserialization

You can create an object (deserialization) by appending `_json` to a string literal:

```cpp
// create object from string literal
json j = "{ \"happy\": true, \"pi\": 3.141 }"_json;

// or even nicer (thanks http://isocpp.org/blog/2015/01/json-for-modern-cpp)
auto j2 = R"(
  {
    "happy": true,
    "pi": 3.141
  }
)"_json;

// or explicitly
auto j3 = json::parse("{ \"happy\": true, \"pi\": 3.141 }");
```

You can also get a string representation (serialize):

```cpp
// explicit conversion to string
std::string s = j.dump();    // {\"happy\":true,\"pi\":3.141}

// serialization with pretty printing
// pass in the amount of spaces to indent
std::cout << j.dump(4) << std::endl;
// {
//     "happy": true,
//     "pi": 3.141
// }
```

You can also use streams to serialize and deserialize:

```cpp
// deserialize from standard input
json j;
Niels's avatar
Niels committed
210
std::cin >> j;
Niels's avatar
Niels committed
211
212
213
214
215
216
217
218
219
220

// serialize to standard output
std::cout << j;

// the setw manipulator was overloaded to set the indentation for pretty printing
std::cout << std::setw(4) << j << std::endl;
```

These operators work for any subclasses of `std::istream` or `std::ostream`.

Kevin Dixon's avatar
Kevin Dixon committed
221
222
Please note that setting the exception bit for `failbit` is inappropriate for this use case. It will result in program termination due to the `noexcept` specifier in use.

Niels's avatar
Niels committed
223
224
### STL-like access

Niels's avatar
Niels committed
225
We designed the JSON class to behave just like an STL container. In fact, it satisfies the [**ReversibleContainer**](http://en.cppreference.com/w/cpp/concept/ReversibleContainer) requirement.
Niels's avatar
Niels committed
226
227
228
229
230
231
232
233
234
235
236
237
238
239

```cpp
// create an array using push_back
json j;
j.push_back("foo");
j.push_back(1);
j.push_back(true);

// iterate the array
for (json::iterator it = j.begin(); it != j.end(); ++it) {
  std::cout << *it << '\n';
}

// range-based for
Niels's avatar
Niels committed
240
for (auto& element : j) {
Niels's avatar
Niels committed
241
242
243
244
245
246
247
248
249
250
251
252
253
254
  std::cout << element << '\n';
}

// getter/setter
const std::string tmp = j[0];
j[1] = 42;
bool foo = j.at(2);

// other stuff
j.size();     // 3 entries
j.empty();    // false
j.type();     // json::value_t::array
j.clear();    // the array is empty again

Niels's avatar
Niels committed
255
256
257
258
259
260
261
262
// convenience type checkers
j.is_null();
j.is_boolean();
j.is_number();
j.is_object();
j.is_array();
j.is_string();

Niels's avatar
Niels committed
263
264
265
266
267
268
269
270
271
// comparison
j == "[\"foo\", 1, true]"_json;  // true

// create an object
json o;
o["foo"] = 23;
o["bar"] = false;
o["baz"] = 3.141;

Niels's avatar
Niels committed
272
273
274
275
276
// special iterator member functions for objects
for (json::iterator it = o.begin(); it != o.end(); ++it) {
  std::cout << it.key() << " : " << it.value() << "\n";
}

Niels's avatar
Niels committed
277
278
279
280
// find an entry
if (o.find("foo") != o.end()) {
  // there is an entry with key "foo"
}
Niels's avatar
Niels committed
281
282
283
284
285
286
287

// or simpler using count()
int foo_present = o.count("foo"); // 1
int fob_present = o.count("fob"); // 0

// delete an entry
o.erase("foo");
Niels's avatar
Niels committed
288
289
290
291
292
293
294
295
296
297
298
```

### Conversion from STL containers

Any sequence container (`std::array`, `std::vector`, `std::deque`, `std::forward_list`, `std::list`) whose values can be used to construct JSON types (e.g., integers, floating point numbers, Booleans, string types, or again STL containers described in this section) can be used to create a JSON array. The same holds for similar associative containers (`std::set`, `std::multiset`, `std::unordered_set`, `std::unordered_multiset`), but in these cases the order of the elements of the array depends how the elements are ordered in the respective STL container.

```cpp
std::vector<int> c_vector {1, 2, 3, 4};
json j_vec(c_vector);
// [1, 2, 3, 4]

Niels's avatar
Niels committed
299
std::deque<double> c_deque {1.2, 2.3, 3.4, 5.6};
Niels's avatar
Niels committed
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
json j_deque(c_deque);
// [1.2, 2.3, 3.4, 5.6]

std::list<bool> c_list {true, true, false, true};
json j_list(c_list);
// [true, true, false, true]

std::forward_list<int64_t> c_flist {12345678909876, 23456789098765, 34567890987654, 45678909876543};
json j_flist(c_flist);
// [12345678909876, 23456789098765, 34567890987654, 45678909876543]

std::array<unsigned long, 4> c_array {{1, 2, 3, 4}};
json j_array(c_array);
// [1, 2, 3, 4]

std::set<std::string> c_set {"one", "two", "three", "four", "one"};
json j_set(c_set); // only one entry for "one" is used
// ["four", "one", "three", "two"]

std::unordered_set<std::string> c_uset {"one", "two", "three", "four", "one"};
json j_uset(c_uset); // only one entry for "one" is used
// maybe ["two", "three", "four", "one"]

std::multiset<std::string> c_mset {"one", "two", "one", "four"};
json j_mset(c_mset); // only one entry for "one" is used
// maybe ["one", "two", "four"]

std::unordered_multiset<std::string> c_umset {"one", "two", "one", "four"};
json j_umset(c_umset); // both entries for "one" are used
// maybe ["one", "two", "one", "four"]
```

Likewise, any associative key-value containers (`std::map`, `std::multimap`, `std::unordered_map`, `std::unordered_multimap`) whose keys are can construct an `std::string` and whose values can be used to construct JSON types (see examples above) can be used to to create a JSON object. Note that in case of multimaps only one key is used in the JSON object and the value depends on the internal order of the STL container.

```cpp
std::map<std::string, int> c_map { {"one", 1}, {"two", 2}, {"three", 3} };
json j_map(c_map);
Annihil's avatar
Annihil committed
337
// {"one": 1, "three": 3, "two": 2 }
Niels's avatar
Niels committed
338

Niels's avatar
Niels committed
339
std::unordered_map<const char*, double> c_umap { {"one", 1.2}, {"two", 2.3}, {"three", 3.4} };
Niels's avatar
Niels committed
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
json j_umap(c_umap);
// {"one": 1.2, "two": 2.3, "three": 3.4}

std::multimap<std::string, bool> c_mmap { {"one", true}, {"two", true}, {"three", false}, {"three", true} };
json j_mmap(c_mmap); // only one entry for key "three" is used
// maybe {"one": true, "two": true, "three": true}

std::unordered_multimap<std::string, bool> c_ummap { {"one", true}, {"two", true}, {"three", false}, {"three", true} };
json j_ummap(c_ummap); // only one entry for key "three" is used
// maybe {"one": true, "two": true, "three": true}
```

### Implicit conversions

The type of the JSON object is determined automatically by the expression to store. Likewise, the stored value is implicitly converted.

```cpp
/// strings
std::string s1 = "Hello, world!";
json js = s1;
std::string s2 = js;

// Booleans
bool b1 = true;
json jb = b1;
bool b2 = jb;

// numbers
int i = 42;
json jn = i;
double f = jn;

// etc.
```

You can also explicitly ask for the value:

```cpp
std::string vs = js.get<std::string>();
bool vb = jb.get<bool>();
int vi = jn.get<int>();

// etc.
```

## License

<img align="right" src="http://opensource.org/trademarks/opensource/OSI-Approved-License-100x137.png">

The class is licensed under the [MIT License](http://opensource.org/licenses/MIT):

Niels's avatar
Niels committed
391
Copyright &copy; 2013-2016 [Niels Lohmann](http://nlohmann.me)
Niels's avatar
Niels committed
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

## Thanks

I deeply appreciate the help of the following people.

- [Teemperor](https://github.com/Teemperor) implemented CMake support and lcov integration, realized escape and Unicode handling in the string parser, and fixed the JSON serialization.
- [elliotgoodrich](https://github.com/elliotgoodrich) fixed an issue with double deletion in the iterator classes.
- [kirkshoop](https://github.com/kirkshoop) made the iterators of the class composable to other libraries.
- [wancw](https://github.com/wanwc) fixed a bug that hindered the class to compile with Clang.
- Tomas Åblad found a bug in the iterator implementation.
Niels's avatar
Niels committed
408
- [Joshua C. Randall](https://github.com/jrandall) fixed a bug in the floating-point serialization.
Niels's avatar
Niels committed
409
- [Aaron Burghardt](https://github.com/aburgh) implemented code to parse streams incrementally. Furthermore, he greatly improved the parser class by allowing the definition of a filter function to discard undesired elements while parsing.
Niels's avatar
Niels committed
410
- [Daniel Kopeček](https://github.com/dkopecek) fixed a bug in the compilation with GCC 5.0.
Niels's avatar
Niels committed
411
- [Florian Weber](https://github.com/Florianjw) fixed a bug in and improved the performance of the comparison operators.
Niels's avatar
Niels committed
412
- [Eric Cornelius](https://github.com/EricMCornelius) pointed out a bug in the handling with NaN and infinity values. He also improved the performance of the string escaping.
Niels's avatar
Niels committed
413
- [易思龙](https://github.com/likebeta) implemented a conversion from anonymous enums.
Niels's avatar
Niels committed
414
- [kepkin](https://github.com/kepkin) patiently pushed forward the support for Microsoft Visual studio.
415
- [gregmarr](https://github.com/gregmarr) simplified the implementation of reverse iterators and helped with numerous hints and improvements.
Niels's avatar
Niels committed
416
- [Caio Luppi](https://github.com/caiovlp) fixed a bug in the Unicode handling.
Niels's avatar
Cleanup    
Niels committed
417
418
419
420
421
- [dariomt](https://github.com/dariomt) fixed some typos in the examples.
- [Daniel Frey](https://github.com/d-frey) cleaned up some pointers and implemented exception-safe memory allocation.
- [Colin Hirsch](https://github.com/ColinH) took care of a small namespace issue.
- [Huu Nguyen](https://github.com/whoshuu) correct a variable name in the documentation.
- [Silverweed](https://github.com/silverweed) overloaded `parse()` to accept an rvalue reference.
Niels's avatar
Niels committed
422
- [dariomt](https://github.com/dariomt) fixed a subtlety in MSVC type support and implemented the `get_ref()` function to get a reference to stored values.
Niels's avatar
Niels committed
423
- [ZahlGraf](https://github.com/ZahlGraf) added a workaround that allows compilation using Android NDK.
Niels's avatar
Niels committed
424
- [whackashoe](https://github.com/whackashoe) replaced a function that was marked as unsafe by Visual Studio.
Niels's avatar
Niels committed
425
- [406345](https://github.com/406345) fixed two small warnings.
Niels's avatar
Niels committed
426
- [Glen Fernandes](https://github.com/glenfe) noted a potential portability problem in the `has_mapped_type` function.
Niels's avatar
thanks    
Niels committed
427
- [Corbin Hughes](https://github.com/nibroc) fixed some typos in the contribution guidelines.
Niels's avatar
Niels committed
428
- [twelsby](https://github.com/twelsby) fixed the array subscript operator, an issue that failed the MSVC build, and floating-point parsing/dumping. He further added support for unsigned integer numbers and implemented better roundtrip support for parsed numbers.
Niels's avatar
thanks    
Niels committed
429
- [Volker Diels-Grabsch](https://github.com/vog) fixed a link in the README file.
Niels's avatar
Niels committed
430
- [msm-](https://github.com/msm-) added support for american fuzzy lop. 
Niels's avatar
Niels committed
431
432
- [Annihil](https://github.com/Annihil) fixed an example in the README file.
- [Themercee](https://github.com/Themercee) noted a wrong URL in the README file.
Niels's avatar
Niels committed
433
434
- [Lv Zheng](https://github.com/lv-zheng) fixed a namespace issue with `int64_t` and `uint64_t`.
- [abc100m](https://github.com/abc100m) analyzed the issues with GCC 4.8 and proposed a [partial solution](https://github.com/nlohmann/json/pull/212).
Niels's avatar
Niels committed
435
- [zewt](https://github.com/zewt) added useful notes to the README file about Android.
Niels's avatar
thanks    
Niels committed
436
437
- [Róbert Márki](https://github.com/robertmrk) added a fix to use move iterators and improved the integration via CMake.
- [Chris Kitching](https://github.com/ChrisKitching) cleaned up the CMake files.
Niels's avatar
Niels committed
438
- [Tom Needham](https://github.com/06needhamt) fixed a subtle bug with MSVC 2015 which was also proposed by [Michael K.](https://github.com/Epidal).
Niels's avatar
Niels committed
439
440
441

Thanks a lot for helping out!

Niels's avatar
Niels committed
442
443
## Notes

444
445
- The code contains numerous debug **assertions** which can be switched off by defining the preprocessor macro `NDEBUG`, see the [documentation of `assert`](http://en.cppreference.com/w/cpp/error/assert).
- As the exact type of a number is not defined in the [JSON specification](http://rfc7159.net/rfc7159), this library tries to choose the best fitting C++ number type automatically. As a result, the type `double` may be used to store numbers which may yield [**floating-point exceptions**](https://github.com/nlohmann/json/issues/181) in certain rare situations if floating-point exceptions have been unmasked in the calling code. These exceptions are not caused by the library and need to be fixed in the calling code, such as by re-masking the exceptions prior to calling library functions.
Niels's avatar
Niels committed
446

Niels's avatar
Niels committed
447
448
449
450
451
452
## Execute unit tests

To compile and run the tests, you need to execute

```sh
$ make
453
$ ./json_unit "*"
Niels's avatar
Niels committed
454
455

===============================================================================
456
All tests passed (5568705 assertions in 31 test cases)
Niels's avatar
Niels committed
457
458
459
```

For more information, have a look at the file [.travis.yml](https://github.com/nlohmann/json/blob/master/.travis.yml).