README.md
1# cJSON
2
3Ultralightweight JSON parser in ANSI C.
4
5## Table of contents
6* [License](#license)
7* [Usage](#usage)
8 * [Welcome to cJSON](#welcome-to-cjson)
9 * [Building](#building)
10 * [Copying the source](#copying-the-source)
11 * [CMake](#cmake)
12 * [Makefile](#makefile)
13 * [Vcpkg](#Vcpkg)
14 * [Including cJSON](#including-cjson)
15 * [Data Structure](#data-structure)
16 * [Working with the data structure](#working-with-the-data-structure)
17 * [Basic types](#basic-types)
18 * [Arrays](#arrays)
19 * [Objects](#objects)
20 * [Parsing JSON](#parsing-json)
21 * [Printing JSON](#printing-json)
22 * [Example](#example)
23 * [Printing](#printing)
24 * [Parsing](#parsing)
25 * [Caveats](#caveats)
26 * [Zero Character](#zero-character)
27 * [Character Encoding](#character-encoding)
28 * [C Standard](#c-standard)
29 * [Floating Point Numbers](#floating-point-numbers)
30 * [Deep Nesting Of Arrays And Objects](#deep-nesting-of-arrays-and-objects)
31 * [Thread Safety](#thread-safety)
32 * [Case Sensitivity](#case-sensitivity)
33 * [Duplicate Object Members](#duplicate-object-members)
34 * [Enjoy cJSON!](#enjoy-cjson)
35
36## License
37
38MIT License
39
40> Copyright (c) 2009-2017 Dave Gamble and cJSON contributors
41>
42> Permission is hereby granted, free of charge, to any person obtaining a copy
43> of this software and associated documentation files (the "Software"), to deal
44> in the Software without restriction, including without limitation the rights
45> to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
46> copies of the Software, and to permit persons to whom the Software is
47> furnished to do so, subject to the following conditions:
48>
49> The above copyright notice and this permission notice shall be included in
50> all copies or substantial portions of the Software.
51>
52> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
53> IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
54> FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
55> AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
56> LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
57> OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
58> THE SOFTWARE.
59
60## Usage
61
62### Welcome to cJSON.
63
64cJSON aims to be the dumbest possible parser that you can get your job done with.
65It's a single file of C, and a single header file.
66
67JSON is described best here: http://www.json.org/
68It's like XML, but fat-free. You use it to move data around, store things, or just
69generally represent your program's state.
70
71As a library, cJSON exists to take away as much legwork as it can, but not get in your way.
72As a point of pragmatism (i.e. ignoring the truth), I'm going to say that you can use it
73in one of two modes: Auto and Manual. Let's have a quick run-through.
74
75I lifted some JSON from this page: http://www.json.org/fatfree.html
76That page inspired me to write cJSON, which is a parser that tries to share the same
77philosophy as JSON itself. Simple, dumb, out of the way.
78
79### Building
80
81There are several ways to incorporate cJSON into your project.
82
83#### copying the source
84
85Because the entire library is only one C file and one header file, you can just copy `cJSON.h` and `cJSON.c` to your projects source and start using it.
86
87cJSON is written in ANSI C (C89) in order to support as many platforms and compilers as possible.
88
89#### CMake
90
91With CMake, cJSON supports a full blown build system. This way you get the most features. CMake with an equal or higher version than 2.8.5 is supported. With CMake it is recommended to do an out of tree build, meaning the compiled files are put in a directory separate from the source files. So in order to build cJSON with CMake on a Unix platform, make a `build` directory and run CMake inside it.
92
93```
94mkdir build
95cd build
96cmake ..
97```
98
99This will create a Makefile and a bunch of other files. You can then compile it:
100
101```
102make
103```
104
105And install it with `make install` if you want. By default it installs the headers `/usr/local/include/cjson` and the libraries to `/usr/local/lib`. It also installs files for pkg-config to make it easier to detect and use an existing installation of CMake. And it installs CMake config files, that can be used by other CMake based projects to discover the library.
106
107You can change the build process with a list of different options that you can pass to CMake. Turn them on with `On` and off with `Off`:
108
109* `-DENABLE_CJSON_TEST=On`: Enable building the tests. (on by default)
110* `-DENABLE_CJSON_UTILS=On`: Enable building cJSON_Utils. (off by default)
111* `-DENABLE_TARGET_EXPORT=On`: Enable the export of CMake targets. Turn off if it makes problems. (on by default)
112* `-DENABLE_CUSTOM_COMPILER_FLAGS=On`: Enable custom compiler flags (currently for Clang, GCC and MSVC). Turn off if it makes problems. (on by default)
113* `-DENABLE_VALGRIND=On`: Run tests with [valgrind](http://valgrind.org). (off by default)
114* `-DENABLE_SANITIZERS=On`: Compile cJSON with [AddressSanitizer](https://github.com/google/sanitizers/wiki/AddressSanitizer) and [UndefinedBehaviorSanitizer](https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html) enabled (if possible). (off by default)
115* `-DENABLE_SAFE_STACK`: Enable the [SafeStack](https://clang.llvm.org/docs/SafeStack.html) instrumentation pass. Currently only works with the Clang compiler. (off by default)
116* `-DBUILD_SHARED_LIBS=On`: Build the shared libraries. (on by default)
117* `-DBUILD_SHARED_AND_STATIC_LIBS=On`: Build both shared and static libraries. (off by default)
118* `-DCMAKE_INSTALL_PREFIX=/usr`: Set a prefix for the installation.
119* `-DENABLE_LOCALES=On`: Enable the usage of localeconv method. ( on by default )
120* `-DCJSON_OVERRIDE_BUILD_SHARED_LIBS=On`: Enable overriding the value of `BUILD_SHARED_LIBS` with `-DCJSON_BUILD_SHARED_LIBS`.
121
122If you are packaging cJSON for a distribution of Linux, you would probably take these steps for example:
123```
124mkdir build
125cd build
126cmake .. -DENABLE_CJSON_UTILS=On -DENABLE_CJSON_TEST=Off -DCMAKE_INSTALL_PREFIX=/usr
127make
128make DESTDIR=$pkgdir install
129```
130
131On Windows CMake is usually used to create a Visual Studio solution file by running it inside the Developer Command Prompt for Visual Studio, for exact steps follow the official documentation from CMake and Microsoft and use the online search engine of your choice. The descriptions of the the options above still generally apply, although not all of them work on Windows.
132
133#### Makefile
134
135**NOTE:** This Method is deprecated. Use CMake if at all possible. Makefile support is limited to fixing bugs.
136
137If you don't have CMake available, but still have GNU make. You can use the makefile to build cJSON:
138
139Run this command in the directory with the source code and it will automatically compile static and shared libraries and a little test program (not the full test suite).
140
141```
142make all
143```
144
145If you want, you can install the compiled library to your system using `make install`. By default it will install the headers in `/usr/local/include/cjson` and the libraries in `/usr/local/lib`. But you can change this behavior by setting the `PREFIX` and `DESTDIR` variables: `make PREFIX=/usr DESTDIR=temp install`. And uninstall them with: `make PREFIX=/usr DESTDIR=temp uninstall`.
146
147#### Vcpkg
148
149You can download and install cJSON using the [vcpkg](https://github.com/Microsoft/vcpkg) dependency manager:
150```
151git clone https://github.com/Microsoft/vcpkg.git
152cd vcpkg
153./bootstrap-vcpkg.sh
154./vcpkg integrate install
155vcpkg install cjson
156```
157
158The cJSON port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please [create an issue or pull request](https://github.com/Microsoft/vcpkg) on the vcpkg repository.
159
160### Including cJSON
161
162If you installed it via CMake or the Makefile, you can include cJSON like this:
163
164```c
165#include <cjson/cJSON.h>
166```
167
168### Data Structure
169
170cJSON represents JSON data using the `cJSON` struct data type:
171
172```c
173/* The cJSON structure: */
174typedef struct cJSON
175{
176 struct cJSON *next;
177 struct cJSON *prev;
178 struct cJSON *child;
179 int type;
180 char *valuestring;
181 /* writing to valueint is DEPRECATED, use cJSON_SetNumberValue instead */
182 int valueint;
183 double valuedouble;
184 char *string;
185} cJSON;
186```
187
188An item of this type represents a JSON value. The type is stored in `type` as a bit-flag (**this means that you cannot find out the type by just comparing the value of `type`**).
189
190To check the type of an item, use the corresponding `cJSON_Is...` function. It does a `NULL` check followed by a type check and returns a boolean value if the item is of this type.
191
192The type can be one of the following:
193
194* `cJSON_Invalid` (check with `cJSON_IsInvalid`): Represents an invalid item that doesn't contain any value. You automatically have this type if you set the item to all zero bytes.
195* `cJSON_False` (check with `cJSON_IsFalse`): Represents a `false` boolean value. You can also check for boolean values in general with `cJSON_IsBool`.
196* `cJSON_True` (check with `cJSON_IsTrue`): Represents a `true` boolean value. You can also check for boolean values in general with `cJSON_IsBool`.
197* `cJSON_NULL` (check with `cJSON_IsNull`): Represents a `null` value.
198* `cJSON_Number` (check with `cJSON_IsNumber`): Represents a number value. The value is stored as a double in `valuedouble` and also in `valueint`. If the number is outside of the range of an integer, `INT_MAX` or `INT_MIN` are used for `valueint`.
199* `cJSON_String` (check with `cJSON_IsString`): Represents a string value. It is stored in the form of a zero terminated string in `valuestring`.
200* `cJSON_Array` (check with `cJSON_IsArray`): Represent an array value. This is implemented by pointing `child` to a linked list of `cJSON` items that represent the values in the array. The elements are linked together using `next` and `prev`, where the first element has `prev.next == NULL` and the last element `next == NULL`.
201* `cJSON_Object` (check with `cJSON_IsObject`): Represents an object value. Objects are stored same way as an array, the only difference is that the items in the object store their keys in `string`.
202* `cJSON_Raw` (check with `cJSON_IsRaw`): Represents any kind of JSON that is stored as a zero terminated array of characters in `valuestring`. This can be used, for example, to avoid printing the same static JSON over and over again to save performance. cJSON will never create this type when parsing. Also note that cJSON doesn't check if it is valid JSON.
203
204Additionally there are the following two flags:
205
206* `cJSON_IsReference`: Specifies that the item that `child` points to and/or `valuestring` is not owned by this item, it is only a reference. So `cJSON_Delete` and other functions will only deallocate this item, not its `child`/`valuestring`.
207* `cJSON_StringIsConst`: This means that `string` points to a constant string. This means that `cJSON_Delete` and other functions will not try to deallocate `string`.
208
209### Working with the data structure
210
211For every value type there is a `cJSON_Create...` function that can be used to create an item of that type.
212All of these will allocate a `cJSON` struct that can later be deleted with `cJSON_Delete`.
213Note that you have to delete them at some point, otherwise you will get a memory leak.
214**Important**: If you have added an item to an array or an object already, you **mustn't** delete it with `cJSON_Delete`. Adding it to an array or object transfers its ownership so that when that array or object is deleted,
215it gets deleted as well. You also could use `cJSON_SetValuestring` to change a `cJSON_String`'s `valuestring`, and you needn't to free the previous `valuestring` manually.
216
217#### Basic types
218
219* **null** is created with `cJSON_CreateNull`
220* **booleans** are created with `cJSON_CreateTrue`, `cJSON_CreateFalse` or `cJSON_CreateBool`
221* **numbers** are created with `cJSON_CreateNumber`. This will set both `valuedouble` and `valueint`. If the number is outside of the range of an integer, `INT_MAX` or `INT_MIN` are used for `valueint`
222* **strings** are created with `cJSON_CreateString` (copies the string) or with `cJSON_CreateStringReference` (directly points to the string. This means that `valuestring` won't be deleted by `cJSON_Delete` and you are responsible for its lifetime, useful for constants)
223
224#### Arrays
225
226You can create an empty array with `cJSON_CreateArray`. `cJSON_CreateArrayReference` can be used to create an array that doesn't "own" its content, so its content doesn't get deleted by `cJSON_Delete`.
227
228To add items to an array, use `cJSON_AddItemToArray` to append items to the end.
229Using `cJSON_AddItemReferenceToArray` an element can be added as a reference to another item, array or string. This means that `cJSON_Delete` will not delete that items `child` or `valuestring` properties, so no double frees are occurring if they are already used elsewhere.
230To insert items in the middle, use `cJSON_InsertItemInArray`. It will insert an item at the given 0 based index and shift all the existing items to the right.
231
232If you want to take an item out of an array at a given index and continue using it, use `cJSON_DetachItemFromArray`, it will return the detached item, so be sure to assign it to a pointer, otherwise you will have a memory leak.
233
234Deleting items is done with `cJSON_DeleteItemFromArray`. It works like `cJSON_DetachItemFromArray`, but deletes the detached item via `cJSON_Delete`.
235
236You can also replace an item in an array in place. Either with `cJSON_ReplaceItemInArray` using an index or with `cJSON_ReplaceItemViaPointer` given a pointer to an element. `cJSON_ReplaceItemViaPointer` will return `0` if it fails. What this does internally is to detach the old item, delete it and insert the new item in its place.
237
238To get the size of an array, use `cJSON_GetArraySize`. Use `cJSON_GetArrayItem` to get an element at a given index.
239
240Because an array is stored as a linked list, iterating it via index is inefficient (`O(n²)`), so you can iterate over an array using the `cJSON_ArrayForEach` macro in `O(n)` time complexity.
241
242#### Objects
243
244You can create an empty object with `cJSON_CreateObject`. `cJSON_CreateObjectReference` can be used to create an object that doesn't "own" its content, so its content doesn't get deleted by `cJSON_Delete`.
245
246To add items to an object, use `cJSON_AddItemToObject`. Use `cJSON_AddItemToObjectCS` to add an item to an object with a name that is a constant or reference (key of the item, `string` in the `cJSON` struct), so that it doesn't get freed by `cJSON_Delete`.
247Using `cJSON_AddItemReferenceToArray` an element can be added as a reference to another object, array or string. This means that `cJSON_Delete` will not delete that items `child` or `valuestring` properties, so no double frees are occurring if they are already used elsewhere.
248
249If you want to take an item out of an object, use `cJSON_DetachItemFromObjectCaseSensitive`, it will return the detached item, so be sure to assign it to a pointer, otherwise you will have a memory leak.
250
251Deleting items is done with `cJSON_DeleteItemFromObjectCaseSensitive`. It works like `cJSON_DetachItemFromObjectCaseSensitive` followed by `cJSON_Delete`.
252
253You can also replace an item in an object in place. Either with `cJSON_ReplaceItemInObjectCaseSensitive` using a key or with `cJSON_ReplaceItemViaPointer` given a pointer to an element. `cJSON_ReplaceItemViaPointer` will return `0` if it fails. What this does internally is to detach the old item, delete it and insert the new item in its place.
254
255To get the size of an object, you can use `cJSON_GetArraySize`, this works because internally objects are stored as arrays.
256
257If you want to access an item in an object, use `cJSON_GetObjectItemCaseSensitive`.
258
259To iterate over an object, you can use the `cJSON_ArrayForEach` macro the same way as for arrays.
260
261cJSON also provides convenient helper functions for quickly creating a new item and adding it to an object, like `cJSON_AddNullToObject`. They return a pointer to the new item or `NULL` if they failed.
262
263### Parsing JSON
264
265Given some JSON in a zero terminated string, you can parse it with `cJSON_Parse`.
266
267```c
268cJSON *json = cJSON_Parse(string);
269```
270
271Given some JSON in a string (whether zero terminated or not), you can parse it with `cJSON_ParseWithLength`.
272
273```c
274cJSON *json = cJSON_ParseWithLength(string, buffer_length);
275```
276
277It will parse the JSON and allocate a tree of `cJSON` items that represents it. Once it returns, you are fully responsible for deallocating it after use with `cJSON_Delete`.
278
279The allocator used by `cJSON_Parse` is `malloc` and `free` by default but can be changed (globally) with `cJSON_InitHooks`.
280
281If an error occurs a pointer to the position of the error in the input string can be accessed using `cJSON_GetErrorPtr`. Note though that this can produce race conditions in multithreading scenarios, in that case it is better to use `cJSON_ParseWithOpts` with `return_parse_end`.
282By default, characters in the input string that follow the parsed JSON will not be considered as an error.
283
284If you want more options, use `cJSON_ParseWithOpts(const char *value, const char **return_parse_end, cJSON_bool require_null_terminated)`.
285`return_parse_end` returns a pointer to the end of the JSON in the input string or the position that an error occurs at (thereby replacing `cJSON_GetErrorPtr` in a thread safe way). `require_null_terminated`, if set to `1` will make it an error if the input string contains data after the JSON.
286
287If you want more options giving buffer length, use `cJSON_ParseWithLengthOpts(const char *value, size_t buffer_length, const char **return_parse_end, cJSON_bool require_null_terminated)`.
288
289### Printing JSON
290
291Given a tree of `cJSON` items, you can print them as a string using `cJSON_Print`.
292
293```c
294char *string = cJSON_Print(json);
295```
296
297It will allocate a string and print a JSON representation of the tree into it. Once it returns, you are fully responsible for deallocating it after use with your allocator. (usually `free`, depends on what has been set with `cJSON_InitHooks`).
298
299`cJSON_Print` will print with whitespace for formatting. If you want to print without formatting, use `cJSON_PrintUnformatted`.
300
301If you have a rough idea of how big your resulting string will be, you can use `cJSON_PrintBuffered(const cJSON *item, int prebuffer, cJSON_bool fmt)`. `fmt` is a boolean to turn formatting with whitespace on and off. `prebuffer` specifies the first buffer size to use for printing. `cJSON_Print` currently uses 256 bytes for its first buffer size. Once printing runs out of space, a new buffer is allocated and the old gets copied over before printing is continued.
302
303These dynamic buffer allocations can be completely avoided by using `cJSON_PrintPreallocated(cJSON *item, char *buffer, const int length, const cJSON_bool format)`. It takes a buffer to a pointer to print to and its length. If the length is reached, printing will fail and it returns `0`. In case of success, `1` is returned. Note that you should provide 5 bytes more than is actually needed, because cJSON is not 100% accurate in estimating if the provided memory is enough.
304
305### Example
306
307In this example we want to build and parse the following JSON:
308
309```json
310{
311 "name": "Awesome 4K",
312 "resolutions": [
313 {
314 "width": 1280,
315 "height": 720
316 },
317 {
318 "width": 1920,
319 "height": 1080
320 },
321 {
322 "width": 3840,
323 "height": 2160
324 }
325 ]
326}
327```
328
329#### Printing
330
331Let's build the above JSON and print it to a string:
332
333```c
334//create a monitor with a list of supported resolutions
335//NOTE: Returns a heap allocated string, you are required to free it after use.
336char *create_monitor(void)
337{
338 const unsigned int resolution_numbers[3][2] = {
339 {1280, 720},
340 {1920, 1080},
341 {3840, 2160}
342 };
343 char *string = NULL;
344 cJSON *name = NULL;
345 cJSON *resolutions = NULL;
346 cJSON *resolution = NULL;
347 cJSON *width = NULL;
348 cJSON *height = NULL;
349 size_t index = 0;
350
351 cJSON *monitor = cJSON_CreateObject();
352 if (monitor == NULL)
353 {
354 goto end;
355 }
356
357 name = cJSON_CreateString("Awesome 4K");
358 if (name == NULL)
359 {
360 goto end;
361 }
362 /* after creation was successful, immediately add it to the monitor,
363 * thereby transferring ownership of the pointer to it */
364 cJSON_AddItemToObject(monitor, "name", name);
365
366 resolutions = cJSON_CreateArray();
367 if (resolutions == NULL)
368 {
369 goto end;
370 }
371 cJSON_AddItemToObject(monitor, "resolutions", resolutions);
372
373 for (index = 0; index < (sizeof(resolution_numbers) / (2 * sizeof(int))); ++index)
374 {
375 resolution = cJSON_CreateObject();
376 if (resolution == NULL)
377 {
378 goto end;
379 }
380 cJSON_AddItemToArray(resolutions, resolution);
381
382 width = cJSON_CreateNumber(resolution_numbers[index][0]);
383 if (width == NULL)
384 {
385 goto end;
386 }
387 cJSON_AddItemToObject(resolution, "width", width);
388
389 height = cJSON_CreateNumber(resolution_numbers[index][1]);
390 if (height == NULL)
391 {
392 goto end;
393 }
394 cJSON_AddItemToObject(resolution, "height", height);
395 }
396
397 string = cJSON_Print(monitor);
398 if (string == NULL)
399 {
400 fprintf(stderr, "Failed to print monitor.\n");
401 }
402
403end:
404 cJSON_Delete(monitor);
405 return string;
406}
407```
408
409Alternatively we can use the `cJSON_Add...ToObject` helper functions to make our lifes a little easier:
410
411```c
412//NOTE: Returns a heap allocated string, you are required to free it after use.
413char *create_monitor_with_helpers(void)
414{
415 const unsigned int resolution_numbers[3][2] = {
416 {1280, 720},
417 {1920, 1080},
418 {3840, 2160}
419 };
420 char *string = NULL;
421 cJSON *resolutions = NULL;
422 size_t index = 0;
423
424 cJSON *monitor = cJSON_CreateObject();
425
426 if (cJSON_AddStringToObject(monitor, "name", "Awesome 4K") == NULL)
427 {
428 goto end;
429 }
430
431 resolutions = cJSON_AddArrayToObject(monitor, "resolutions");
432 if (resolutions == NULL)
433 {
434 goto end;
435 }
436
437 for (index = 0; index < (sizeof(resolution_numbers) / (2 * sizeof(int))); ++index)
438 {
439 cJSON *resolution = cJSON_CreateObject();
440
441 if (cJSON_AddNumberToObject(resolution, "width", resolution_numbers[index][0]) == NULL)
442 {
443 goto end;
444 }
445
446 if (cJSON_AddNumberToObject(resolution, "height", resolution_numbers[index][1]) == NULL)
447 {
448 goto end;
449 }
450
451 cJSON_AddItemToArray(resolutions, resolution);
452 }
453
454 string = cJSON_Print(monitor);
455 if (string == NULL)
456 {
457 fprintf(stderr, "Failed to print monitor.\n");
458 }
459
460end:
461 cJSON_Delete(monitor);
462 return string;
463}
464```
465
466#### Parsing
467
468In this example we will parse a JSON in the above format and check if the monitor supports a Full HD resolution while printing some diagnostic output:
469
470```c
471/* return 1 if the monitor supports full hd, 0 otherwise */
472int supports_full_hd(const char * const monitor)
473{
474 const cJSON *resolution = NULL;
475 const cJSON *resolutions = NULL;
476 const cJSON *name = NULL;
477 int status = 0;
478 cJSON *monitor_json = cJSON_Parse(monitor);
479 if (monitor_json == NULL)
480 {
481 const char *error_ptr = cJSON_GetErrorPtr();
482 if (error_ptr != NULL)
483 {
484 fprintf(stderr, "Error before: %s\n", error_ptr);
485 }
486 status = 0;
487 goto end;
488 }
489
490 name = cJSON_GetObjectItemCaseSensitive(monitor_json, "name");
491 if (cJSON_IsString(name) && (name->valuestring != NULL))
492 {
493 printf("Checking monitor \"%s\"\n", name->valuestring);
494 }
495
496 resolutions = cJSON_GetObjectItemCaseSensitive(monitor_json, "resolutions");
497 cJSON_ArrayForEach(resolution, resolutions)
498 {
499 cJSON *width = cJSON_GetObjectItemCaseSensitive(resolution, "width");
500 cJSON *height = cJSON_GetObjectItemCaseSensitive(resolution, "height");
501
502 if (!cJSON_IsNumber(width) || !cJSON_IsNumber(height))
503 {
504 status = 0;
505 goto end;
506 }
507
508 if ((width->valuedouble == 1920) && (height->valuedouble == 1080))
509 {
510 status = 1;
511 goto end;
512 }
513 }
514
515end:
516 cJSON_Delete(monitor_json);
517 return status;
518}
519```
520
521Note that there are no NULL checks except for the result of `cJSON_Parse` because `cJSON_GetObjectItemCaseSensitive` checks for `NULL` inputs already, so a `NULL` value is just propagated and `cJSON_IsNumber` and `cJSON_IsString` return `0` if the input is `NULL`.
522
523### Caveats
524
525#### Zero Character
526
527cJSON doesn't support strings that contain the zero character `'\0'` or `\u0000`. This is impossible with the current API because strings are zero terminated.
528
529#### Character Encoding
530
531cJSON only supports UTF-8 encoded input. In most cases it doesn't reject invalid UTF-8 as input though, it just propagates it through as is. As long as the input doesn't contain invalid UTF-8, the output will always be valid UTF-8.
532
533#### C Standard
534
535cJSON is written in ANSI C (or C89, C90). If your compiler or C library doesn't follow this standard, correct behavior is not guaranteed.
536
537NOTE: ANSI C is not C++ therefore it shouldn't be compiled with a C++ compiler. You can compile it with a C compiler and link it with your C++ code however. Although compiling with a C++ compiler might work, correct behavior is not guaranteed.
538
539#### Floating Point Numbers
540
541cJSON does not officially support any `double` implementations other than IEEE754 double precision floating point numbers. It might still work with other implementations but bugs with these will be considered invalid.
542
543The maximum length of a floating point literal that cJSON supports is currently 63 characters.
544
545#### Deep Nesting Of Arrays And Objects
546
547cJSON doesn't support arrays and objects that are nested too deeply because this would result in a stack overflow. To prevent this cJSON limits the depth to `CJSON_NESTING_LIMIT` which is 1000 by default but can be changed at compile time.
548
549#### Thread Safety
550
551In general cJSON is **not thread safe**.
552
553However it is thread safe under the following conditions:
554
555* `cJSON_GetErrorPtr` is never used (the `return_parse_end` parameter of `cJSON_ParseWithOpts` can be used instead)
556* `cJSON_InitHooks` is only ever called before using cJSON in any threads.
557* `setlocale` is never called before all calls to cJSON functions have returned.
558
559#### Case Sensitivity
560
561When cJSON was originally created, it didn't follow the JSON standard and didn't make a distinction between uppercase and lowercase letters. If you want the correct, standard compliant, behavior, you need to use the `CaseSensitive` functions where available.
562
563#### Duplicate Object Members
564
565cJSON supports parsing and printing JSON that contains objects that have multiple members with the same name. `cJSON_GetObjectItemCaseSensitive` however will always only return the first one.
566
567# Enjoy cJSON!
568
569- Dave Gamble (original author)
570- Max Bruckner and Alan Wang (current maintainer)
571- and the other [cJSON contributors](CONTRIBUTORS.md)
572