cjson添加字段flag

{ "config": { "meshList": [{ "childAPs": [{ "mac": "00-00-FF-FC-0A-00", "radioId": 1 }], "mac": "58-71-10-D3-E1-AB" }, { "childAPs": [{ "mac": "00-00-FF-FC-39-00", "radioId": 1 }]在"childAPs"字段中加入新的item"flag",设置数值为3

当然！以下是如何在 cJSON 数据结构中为 childAPs 字段添加新的 flag 项并将其值设置为 3 的示例代码：

示例代码

#include "cJSON.h"
#include <stdio.h>

int main() {
    const char *jsonString = "{\"config\": {\"meshList\": [{\"childAPs\": [{\"mac\": \"00-00-FF-FC-0A-00\",\"radioId\": 1}],\"mac\": \"58-71-10-D3-E1-AB\"}, {\"childAPs\": [{\"mac\": \"00-00-FF-FC-39-00\",\"radioId\": 1}],\"mac\": \"00-00-FF-FC-0A-00\"}]}}";
    
    // 解析 JSON 字符串
    cJSON *pJson = cJSON_Parse(jsonString);
    if (pJson == NULL) {
        printf("Error parsing JSON.\n");
        return -1;
    }

    // 查找 "config"
    cJSON *config = cJSON_GetObjectItem(pJson, "config");
    if (config == NULL) {
        printf("Cannot find 'config'.\n");
        cJSON_Delete(pJson);
        return -1;
    }

    // 查找 "meshList"
    cJSON *meshList = cJSON_GetObjectItem(config, "meshList");
    if (meshList == NULL) {
        printf("Cannot find 'meshList'.\n");
        cJSON_Delete(pJson);
        return -1;
    }

    // 遍历 "meshList" 中的对象
    for (int i = 0; i < cJSON_GetArraySize(meshList); i++) {
        cJSON *meshItem = cJSON_GetArrayItem(meshList, i);
        if (meshItem == NULL) {
            printf("Cannot find mesh item at index %d.\n", i);
            continue;
        }

        // 查找 "childAPs"
        cJSON *childAPs = cJSON_GetObjectItem(meshItem, "childAPs");
        if (childAPs == NULL) {
            printf("Cannot find 'childAPs' in mesh item at index %d.\n", i);
            continue;
        }

        // 遍历并添加 "flag" 字段
        for (int j = 0; j < cJSON_GetArraySize(childAPs); j++) {
            cJSON *childAP = cJSON_GetArrayItem(childAPs, j);
            if (childAP == NULL) {
                printf("Cannot find child AP at index %d in mesh item %d.\n", j, i);
                continue;
            }

            // 添加 "flag" 字段并设置值为 3
            cJSON_AddNumberToObject(childAP, "flag", 3);
        }
    }

    // 打印修改后的 JSON
    char *modifiedJsonString = cJSON_PrintUnformatted(pJson);
    if (modifiedJsonString != NULL) {
        printf("Modified JSON:\n%s\n", modifiedJsonString);
        cJSON_free(modifiedJsonString);
    }

    // 释放内存
    cJSON_Delete(pJson);

    return 0;
}

代码解释

1. 解析 JSON 字符串：

   c

   cJSON *pJson = cJSON_Parse(jsonString);
   if (pJson == NULL) {
       printf("Error parsing JSON.\n");
       return -1;
   }
   

2. 查找 config 对象：

   c

   cJSON *config = cJSON_GetObjectItem(pJson, "config");
   if (config == NULL) {
       printf("Cannot find 'config'.\n");
       cJSON_Delete(pJson);
       return -1;
   }
   

3. 查找 meshList 对象：

   c

   cJSON *meshList = cJSON_GetObjectItem(config, "meshList");
   if (meshList == NULL) {
       printf("Cannot find 'meshList'.\n");
       cJSON_Delete(pJson);
       return -1;
   }
   

4. 遍历 meshList 中的对象：

   c

   for (int i = 0; i < cJSON_GetArraySize(meshList); i++) {
       cJSON *meshItem = cJSON_GetArrayItem(meshList, i);
       if (meshItem == NULL) {
           printf("Cannot find mesh item at index %d.\n", i);
           continue;
       }
   
       // 查找 "childAPs"
       cJSON *childAPs = cJSON_GetObjectItem(meshItem, "childAPs");
       if (childAPs == NULL) {
           printf("Cannot find 'childAPs' in mesh item at index %d.\n", i);
           continue;
       }
   
       // 遍历并添加 "flag" 字段
       for (int j = 0; j < cJSON_GetArraySize(childAPs); j++) {
           cJSON *childAP = cJSON_GetArrayItem(childAPs, j);
           if (childAP == NULL) {
               printf("Cannot find child AP at index %d in mesh item %d.\n", j, i);
               continue;
           }
   
           // 添加 "flag" 字段并设置值为 3
           cJSON_AddNumberToObject(childAP, "flag", 3);
       }
   }
   

5. 打印修改后的 JSON：

   c

   char *modifiedJsonString = cJSON_PrintUnformatted(pJson);
   if (modifiedJsonString != NULL) {
       printf("Modified JSON:\n%s\n", modifiedJsonString);
       cJSON_free(modifiedJsonString);
   }
   

6. 释放内存：

   c

   cJSON_Delete(pJson);
   

运行上述代码后，childAPs 字段中的每个对象将包含新的 flag 字段，其值为 3。修改后的 JSON 将打印出来。