json文件写操作-下文

接上文json文件写操作

2.4 控制函数长度代码规范版

#include <iostream>
#include <string>
#include "../3rd/cJSON/cJSON.h"
#include "../test_memset/include/ArrayToZero.h"using namespace std;void AddLikeObject(cJSON* interest, cJSON* final, cJSON* likeObject1, cJSON* likeObject2, cJSON* like)
{// 插入元素，对应 键值对cJSON_AddItemToObject(interest, "combat",cJSON_CreateString("热血"));        // 当值是字符串时，需要使用函数cJSON_CreateString()创建cJSON_AddItemToObject(interest, "reasoning", cJSON_CreateString("推理"));// 或者使用宏进行添加//cJSON_AddStringToObject(interest, "reasoning", "推理");    // 或者这样写// 2.定义 [ ] 数组// 往数组中添加元素cJSON_AddItemToArray(final, cJSON_CreateString("BE"));cJSON_AddItemToArray(final, cJSON_CreateString("HE"));// 3.定义 { } 对象cJSON_AddItemToObject(likeObject1, "game", cJSON_CreateString("斩赤红之瞳"));cJSON_AddItemToObject(likeObject1, "Episodes",cJSON_CreateNumber(22));        // 当值是数字时，需要使用函数cJSON_CreateNumber()创建//cJSON_AddNumberToObject(likeObject1, "price", 66.6);    // 或者这样写cJSON_AddItemToObject(likeObject2, "game", cJSON_CreateString("文豪野犬"));cJSON_AddItemToObject(likeObject2, "Episodes", cJSON_CreateNumber(84));// 4.定义 [ ] 数组// 往数组中添加元素cJSON_AddItemToArray(like, likeObject1);cJSON_AddItemToArray(like, likeObject2);
}void AddEducationObject(cJSON* education1, cJSON* education2, cJSON* education, cJSON* serialOne, cJSON* serialTwo, cJSON* languages)
{// 定义 [ ] 数组cJSON_AddItemToArray(education1, cJSON_CreateString("战斗"));cJSON_AddItemToArray(education1, cJSON_CreateString("热血"));cJSON_AddItemToArray(education2, cJSON_CreateString("推理"));cJSON_AddItemToArray(education2, cJSON_CreateString("格斗"));// 5.定义 [ ] 数组/*"languages": {"serialOne": { "language": "汉语", "grade" : 10 },"serialTwo" : { "language": "英语", "grade" : 6}}*/cJSON_AddItemToArray(education, education1);cJSON_AddItemToArray(education, education2);// 定义对象 { }cJSON_AddItemToObject(serialOne, "language", cJSON_CreateString("汉语"));cJSON_AddItemToObject(serialOne, "grade", cJSON_CreateNumber(10));cJSON_AddItemToObject(serialTwo, "language", cJSON_CreateString("英语"));cJSON_AddItemToObject(serialTwo, "grade", cJSON_CreateNumber(6));// 定义对象 { }cJSON_AddItemToObject(languages, "serialOne", serialOne);cJSON_AddItemToObject(languages, "serialTwo", serialTwo);
}void json_write()
{//1. 定义对象 { }cJSON* interest = cJSON_CreateObject();cJSON* final = cJSON_CreateArray();cJSON* likeObject1 = cJSON_CreateObject();cJSON* likeObject2 = cJSON_CreateObject();cJSON* like = cJSON_CreateArray();cJSON* education1 = cJSON_CreateArray();cJSON* education2 = cJSON_CreateArray();cJSON* education = cJSON_CreateArray();cJSON* serialOne = cJSON_CreateObject();cJSON* serialTwo = cJSON_CreateObject();cJSON* languages = cJSON_CreateObject();cJSON* root = cJSON_CreateObject();if (interest == nullptr || final == nullptr || likeObject1 == nullptr || likeObject2 == nullptr ||like == nullptr || education1 == nullptr || education2 == nullptr || education == nullptr ||serialOne == nullptr || serialTwo == nullptr || languages == nullptr || root == nullptr) {cJSON_Delete(interest);cJSON_Delete(final);cJSON_Delete(likeObject1);cJSON_Delete(likeObject2);cJSON_Delete(like);cJSON_Delete(education1);cJSON_Delete(education2);cJSON_Delete(education);cJSON_Delete(serialOne);cJSON_Delete(serialTwo);cJSON_Delete(languages);cJSON_Delete(root);return;}AddLikeObject(interest, final, likeObject1, likeObject2, like);AddEducationObject(education1, education2, education, serialOne, serialTwo, languages);// 将子项插入根项中cJSON_AddItemToObject(root, "name", cJSON_CreateString("Blue"));cJSON_AddItemToObject(root, "age", cJSON_CreateNumber(25));cJSON_AddItemToObject(root, "interest", interest);cJSON_AddItemToObject(root, "final", final);cJSON_AddItemToObject(root, "like", like);cJSON_AddItemToObject(root, "education", education);cJSON_AddItemToObject(root, "languages", languages);cJSON_AddItemToObject(root, "vip", cJSON_CreateTrue());    // "vip":    true        插入布尔类型数据需要使用cJSON_CreateBool函数cJSON_AddItemToObject(root, "address",cJSON_CreateNull());    // "address":    null    插入NULL值需要使用cJSON_CreateNull函数//cJSON_AddTrueToObject(root, "vip");//cJSON_AddNullToObject(root, "address");    // 或者这样写也是可以的// 控制台输出char* ALL_JSON = cJSON_Print(root);char* ALL_JSONUnformatted = cJSON_PrintUnformatted(root);
#ifdef TRACK_TESTprintf("ALL_JSON：\n%s\n", ALL_JSON);                          // ALL_JSON：有做格式调整printf("ALL_JSONUnformatted：\n%s\n", ALL_JSONUnformatted);    // cJSON_PrintUnformatted：没有做格式调整
#endif// 返回的字符串指针需要自己释放free(ALL_JSON);free(ALL_JSONUnformatted);//****************************************************************// 打开文件FILE* file = NULL;file = fopen("E:\\abs\\test.json", "w");if (file == NULL) {printf("Open file fail！\n");// 释放指针内存cJSON_Delete(root);return;}char* cjValue = cJSON_Print(root);// 写入文件//int ret = fwrite(cjValue, sizeof(char), strlen(cjValue), file);int ret = fputs(cjValue, file);if (ret == EOF) {printf("写入文件失败！\n");}fclose(file);free(cjValue);// 释放指针内存cJSON_Delete(root);
}int main()
{cout << "test CJSON" << "hello" << endl;ArrayToZero arrayToZero;arrayToZero.showArray();json_write();return 0;
}

2.6 CMakelist.txt

cmake_minimum_required(VERSION 3.16.5)message("this is cmakelist log")
message(${CMAKE_CURRENT_SOURCE_DIR})get_filename_component(ProjectId ${CMAKE_CURRENT_SOURCE_DIR} NAME)
message(${ProjectId})
message(${ProjectId})
message(NAME)
string(REPLACE " " "_" ProjectId ${ProjectId})
message(${ProjectId})#project(${ProjectId} CXX)
project(${ProjectId})SET(CMAKE_CXX_COMPILER "g++")
SET(CMAKE_C_COMPILER "gcc")#添加宏定义Debug为CMAKE_BUILD_TYPE
SET(CMAKE_BUILD_TYPE "Release")
SET(CMAKE_BUILD_TYPE "Debug")
SET(PLATFORM "LINUX")add_definitions(-DCLUSTER_DEBUG)
add_definitions(-DCOMBINE_WEEKDAY)set(CMAKE_CXX_STANDARD 17)if (CMAKE_BUILD_TYPE STREQUAL Debug)set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g -D_DEBUG")
else ()set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -D_FORTIFY_SOURCE=2 -O3 -DNDEBUG -s")
endif ()if (PLATFORM STREQUAL WINDOWS OR PLATFORM STREQUAL windows)SET(PLATFORM windows)add_definitions(-DWIN32)
else ()SET(PLATFORM linux)add_definitions(-Dlinux)
endif()add_definitions(-DTRACK_TEST
)#添加头文件
#例如：include_directories(/usr/include/abc /usr/include/xxx)
#是将“/usr/include/abc”和“/usr/include/xxx”这两个目录添加至编译器的头文件搜索目录(两个目录用空格分隔)。
include_directories(../3rd/cJSON)
include_directories(../test_memset/include/)
#通过编译源文件来创建一个可执行文件，其中，name是生成的可执行文件的名称，source是创建可执行文件所需要的源文件。
#源文件可以使用aux_source_directory指令返回的变量（将源文件保存在这个变量中）,也可以是指定的.cpp文件（注意路径）。
aux_source_directory(../3rd/cJSON cJSONSrc)
aux_source_directory(../test_memset/src memsetSrc)add_executable(${ProjectId}${memsetSrc}${cJSONSrc}main.cpp)

2.5 关于指针释放

其中需要注意的是，增加下面的语句会出现报错。原因是这里只调用cJSON_Delete(root)就可以了，zeroError，zeroErrorIntersection，finalTime，relatively都挂在了root下面。

//    cJSON_Delete(zeroError);
//    cJSON_Delete(zeroErrorIntersection);
//    cJSON_Delete(finalTime);
//    cJSON_Delete(relatively);

2.6 关于external"C"

然后上述代码，如果删除掉下面的代码好像也不影响，不知道为什么。

#ifdef __cplusplus
extern "C" {
#endif

然后我就在想是不是因为我引用的某个文件已经加了这个定义，然后整个工程就有了这个定义。我在cJSON.h文件中确实发现了上面c++的定义，我现在尝试注释掉这个宏定义，然后再次编译，确实报错了。

所以我现在突然理解了，就是想调用c文件，或者应该这样说，这个c文件想被其他文件调用，就应该在头文件中定义extren “C”，这样其他c++文件就可以正常调用这个c文件。OK!

2.7 验证指针挂载

下面验证cJSON_AddItemToArray(education, education1);这个语句是否是将education1指针挂在在education上，

写测试代码

cJSON_Delete(education1);
cJSON_Delete(education2);
cJSON_Delete(education);

运行程序提示free(): double free detected in tcache 2，所以确实是将education1挂在education上了。只需要释放一次，跟上述root一样处理。

三、错误处理

/usr/bin/ld: CMakeFiles/testCJSON.dir/main.cpp.o: in function `json_write()':
/data2/z30031397/myProjTest/test_CJSON/main.cpp:15: undefined reference to `cJSON_CreateObject'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:17: undefined reference to `cJSON_CreateString'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:17: undefined reference to `cJSON_AddItemToObject'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:18: undefined reference to `cJSON_CreateString'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:18: undefined reference to `cJSON_AddItemToObject'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:23: undefined reference to `cJSON_CreateArray'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:25: undefined reference to `cJSON_CreateString'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:25: undefined reference to `cJSON_AddItemToArray'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:26: undefined reference to `cJSON_CreateString'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:26: undefined reference to `cJSON_AddItemToArray'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:30: undefined reference to `cJSON_CreateObject'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:31: undefined reference to `cJSON_CreateString'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:31: undefined reference to `cJSON_AddItemToObject'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:32: undefined reference to `cJSON_CreateNumber'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:32: undefined reference to `cJSON_AddItemToObject'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:35: undefined reference to `cJSON_CreateObject'
/usr/bin/ld: /data2/z30031397/myProjTest/test_CJSON/main.cpp:36: undefined reference to `cJSON_CreateString'