cJSON：封装与解析（二）

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该篇介绍使用 cJSON 封装和解析数组。cJSON的简单使用请看这篇。

测试字符串：

{"name":	"children info","info":	[{"name":	"lilei","age":	5,"height":	0.45}, {"name":	"lily","age":	4,"height":	0.35}, {"name":	"hanmeimei","age":	4,"height":	0.4}]
}

1. 封装

enum json_print_formate
{PRINT_FORMATE = 0,    /*按 json 格式输出*/PRINT_UNFORMATE,      /*以字符串形式输出*/
};char *json_array_package(enum json_print_formate flag)
{cJSON *root = NULL; cJSON *info = NULL;cJSON *child_info = NULL;char *out = NULL;root = cJSON_CreateObject(); /*创建 json 根节点*/cJSON_AddStringToObject(root, "name", "children info");  /*添加字符串*/info = cJSON_CreateArray(); /*创建 json 数组*/cJSON_AddItemToObject(root, "info", info);    /*将数组加入到根节点*/child_info = cJSON_CreateObject();    /*向数组中添加成员*/cJSON_AddItemToArray(info, child_info);cJSON_AddStringToObject(child_info, "name", "lilei");  /*添加字符串*/cJSON_AddNumberToObject(child_info, "age", 5);      /*添加整型*/cJSON_AddNumberToObject(child_info, "height", 0.45);  /*添加浮点型*/child_info = cJSON_CreateObject();    /*向数组中添加成员*/cJSON_AddItemToArray(info, child_info);cJSON_AddStringToObject(child_info, "name", "lily");  /*添加字符串*/cJSON_AddNumberToObject(child_info, "age", 4);      /*添加整型*/cJSON_AddNumberToObject(child_info, "height", 0.35);  /*添加浮点型*/child_info = cJSON_CreateObject();    /*向数组中添加成员*/cJSON_AddItemToArray(info, child_info);cJSON_AddStringToObject(child_info, "name", "hanmeimei");  /*添加字符串*/cJSON_AddNumberToObject(child_info, "age", 4);      /*添加整型*/cJSON_AddNumberToObject(child_info, "height", 0.40);  /*添加浮点型*/if(PRINT_FORMATE == flag){out = cJSON_Print(root);   }else{out = cJSON_PrintUnformatted(root);    /*将json形式打印成正常字符串形式*/}/*释放内存*/  cJSON_Delete(root);     return out;  
}

2. 解析

void json_array_parse(char *json_string)
{cJSON *root = NULL;    /*json 根节点*/cJSON *name = NULL;cJSON *jarray = NULL;    /*json 数组*/cJSON *member = NULL;cJSON *age = NULL;cJSON *height = NULL;root = cJSON_Parse(json_string);name = cJSON_GetObjectItem( root , "name" );printf("root name:%s\n", name->valuestring);jarray = cJSON_GetObjectItem(root, "info");cJSON_ArrayForEach(member, jarray)    /*遍历数组*/{name = cJSON_GetObjectItem( member , "name" );age = cJSON_GetObjectItem( member , "age" );height = cJSON_GetObjectItem( member , "height" );printf("name:%s, age:%d, height:%f\n", name->valuestring, age->valueint, height->valuedouble);}/*释放内存*/  cJSON_Delete(root);     
}

3. 测试

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include"cJSON.h"int main()
{char *json_str = NULL;json_str = json_array_package(PRINT_FORMATE);printf("array formate:\n%s\n", json_str);json_array_parse(json_str);cJSON_free(json_str);json_str = json_array_package(PRINT_UNFORMATE);printf("\narray unformate:\n%s\n", json_str);json_array_parse(json_str);cJSON_free(json_str);}

   CMakeLists.txt

cmake_minimum_required(VERSION 3.5)project(json_test)include_directories(./)aux_source_directory(./ SRC_FILES)add_executable(${PROJECT_NAME} ${SRC_FILES})

4. 结果

array formate:
{"name":	"children info","info":	[{"name":	"lilei","age":	5,"height":	0.45}, {"name":	"lily","age":	4,"height":	0.35}, {"name":	"hanmeimei","age":	4,"height":	0.4}]
}
root name:children info
name:lilei, age:5, height:0.450000
name:lily, age:4, height:0.350000
name:hanmeimei, age:4, height:0.400000array unformate:
{"name":"children info","info":[{"name":"lilei","age":5,"height":0.45},{"name":"lily","age":4,"height":0.35},{"name":"hanmeimei","age":4,"height":0.4}]}
root name:children info
name:lilei, age:5, height:0.450000
name:lily, age:4, height:0.350000
name:hanmeimei, age:4, height:0.400000

Note：

cJSON_Print(const cJSON *item) 和 cJSON_PrintUnformatted(const cJSON *item) 这两个函数会调用 malloc 分配内存，需要调用 cJSON_free(void *object) 进行释放。

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