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README.OpenSource
1 [ 2 { 3 "Name": "cJSON", 4 "License": "MIT License", 5 "License File": "LICENSE", 6 "Version Number": "1.7.15", 7 "Owner": "lizhiqi1@huawei.com", 8 "Upstream URL": "https://github.com/DaveGamble/cJSON/releases", 9 "Description": "Ultralightweight JSON parser in ANSI C." 10 } 11 ] 12 13
README.md
1 # cJSON 2 3 Ultralightweight 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 38 MIT 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 64 cJSON aims to be the dumbest possible parser that you can get your job done with. 65 It's a single file of C, and a single header file. 66 67 JSON is described best here: http://www.json.org/ 68 It's like XML, but fat-free. You use it to move data around, store things, or just 69 generally represent your program's state. 70 71 As a library, cJSON exists to take away as much legwork as it can, but not get in your way. 72 As a point of pragmatism (i.e. ignoring the truth), I'm going to say that you can use it 73 in one of two modes: Auto and Manual. Let's have a quick run-through. 74 75 I lifted some JSON from this page: http://www.json.org/fatfree.html 76 That page inspired me to write cJSON, which is a parser that tries to share the same 77 philosophy as JSON itself. Simple, dumb, out of the way. 78 79 ### Building 80 81 There are several ways to incorporate cJSON into your project. 82 83 #### copying the source 84 85 Because 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 87 cJSON is written in ANSI C (C89) in order to support as many platforms and compilers as possible. 88 89 #### CMake 90 91 With 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 ``` 94 mkdir build 95 cd build 96 cmake .. 97 ``` 98 99 This will create a Makefile and a bunch of other files. You can then compile it: 100 101 ``` 102 make 103 ``` 104 105 And 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. 106 107 You 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`. 121 122 If you are packaging cJSON for a distribution of Linux, you would probably take these steps for example: 123 ``` 124 mkdir build 125 cd build 126 cmake .. -DENABLE_CJSON_UTILS=On -DENABLE_CJSON_TEST=Off -DCMAKE_INSTALL_PREFIX=/usr 127 make 128 make DESTDIR=$pkgdir install 129 ``` 130 131 On 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. 136 137 If you don't have CMake available, but still have GNU make. You can use the makefile to build cJSON: 138 139 Run 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 ``` 142 make all 143 ``` 144 145 If 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 148 149 You can download and install cJSON using the [vcpkg](https://github.com/Microsoft/vcpkg) dependency manager: 150 ``` 151 git clone https://github.com/Microsoft/vcpkg.git 152 cd vcpkg 153 ./bootstrap-vcpkg.sh 154 ./vcpkg integrate install 155 vcpkg install cjson 156 ``` 157 158 The 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 161 162 If 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 169 170 cJSON represents JSON data using the `cJSON` struct data type: 171 172 ```c 173 /* The cJSON structure: */ 174 typedef 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 ``` 187 188 An 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`**). 189 190 To 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. 191 192 The 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. 203 204 Additionally 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 210 211 For every value type there is a `cJSON_Create...` function that can be used to create an item of that type. 212 All of these will allocate a `cJSON` struct that can later be deleted with `cJSON_Delete`. 213 Note 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, 215 it 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 225 226 You 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`. 227 228 To add items to an array, use `cJSON_AddItemToArray` to append items to the end. 229 Using `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. 230 To 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. 231 232 If 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. 233 234 Deleting items is done with `cJSON_DeleteItemFromArray`. It works like `cJSON_DetachItemFromArray`, but deletes the detached item via `cJSON_Delete`. 235 236 You 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. 237 238 To get the size of an array, use `cJSON_GetArraySize`. Use `cJSON_GetArrayItem` to get an element at a given index. 239 240 Because 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 243 244 You 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`. 245 246 To 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`. 247 Using `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. 248 249 If 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. 250 251 Deleting items is done with `cJSON_DeleteItemFromObjectCaseSensitive`. It works like `cJSON_DetachItemFromObjectCaseSensitive` followed by `cJSON_Delete`. 252 253 You 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. 254 255 To get the size of an object, you can use `cJSON_GetArraySize`, this works because internally objects are stored as arrays. 256 257 If you want to access an item in an object, use `cJSON_GetObjectItemCaseSensitive`. 258 259 To iterate over an object, you can use the `cJSON_ArrayForEach` macro the same way as for arrays. 260 261 cJSON 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 264 265 Given some JSON in a zero terminated string, you can parse it with `cJSON_Parse`. 266 267 ```c 268 cJSON *json = cJSON_Parse(string); 269 ``` 270 271 Given some JSON in a string (whether zero terminated or not), you can parse it with `cJSON_ParseWithLength`. 272 273 ```c 274 cJSON *json = cJSON_ParseWithLength(string, buffer_length); 275 ``` 276 277 It 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`. 278 279 The allocator used by `cJSON_Parse` is `malloc` and `free` by default but can be changed (globally) with `cJSON_InitHooks`. 280 281 If 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`. 282 By default, characters in the input string that follow the parsed JSON will not be considered as an error. 283 284 If 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. 286 287 If 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 290 291 Given a tree of `cJSON` items, you can print them as a string using `cJSON_Print`. 292 293 ```c 294 char *string = cJSON_Print(json); 295 ``` 296 297 It 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`. 300 301 If 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. 302 303 These 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 306 307 In 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 330 331 Let'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. 336 char *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 } 402 403 end: 404 cJSON_Delete(monitor); 405 return string; 406 } 407 ``` 408 409 Alternatively 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. 413 char *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 } 459 460 end: 461 cJSON_Delete(monitor); 462 return string; 463 } 464 ``` 465 466 #### Parsing 467 468 In 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 */ 472 int 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 } 514 515 end: 516 cJSON_Delete(monitor_json); 517 return status; 518 } 519 ``` 520 521 Note 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 526 527 cJSON 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 530 531 cJSON 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 534 535 cJSON is written in ANSI C (or C89, C90). If your compiler or C library doesn't follow this standard, correct behavior is not guaranteed. 536 537 NOTE: 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 540 541 cJSON 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. 542 543 The maximum length of a floating point literal that cJSON supports is currently 63 characters. 544 545 #### Deep Nesting Of Arrays And Objects 546 547 cJSON 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 550 551 In general cJSON is **not thread safe**. 552 553 However 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 560 561 When 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 564 565 cJSON 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