cJSON

转载：https://github.com/DaveGamble/cJSON

cJSON的使用：

把这两个文件放到自己的工程

实例:

建立和解析这个json格式的字符串

{
    "name": "Awesome 4K",
    "resolutions": [
        {
            "width": 1280,
            "height": 720
        },
        {
            "width": 1920,
            "height": 1080
        },
        {
            "width": 3840,
            "height": 2160
        }
    ]
}

  1 #include<iostream>
  2 #include"cJSON.h"
  3 
  4 using namespace std;
  5 
  6 //create a monitor with a list of supported resolutions
  7 //NOTE: Returns a heap allocated string, you are required to free it after use.
  8 char *create_monitor(void)
  9 {
 10     const unsigned int resolution_numbers[3][2] = {
 11         {1280, 720},
 12         {1920, 1080},
 13         {3840, 2160}
 14     };
 15     char *string = NULL;
 16     cJSON *name = NULL;
 17     cJSON *resolutions = NULL;
 18     cJSON *resolution = NULL;
 19     cJSON *width = NULL;
 20     cJSON *height = NULL;
 21     size_t index = 0;
 22 
 23     cJSON *monitor = cJSON_CreateObject();
 24     if (monitor == NULL)
 25     {
 26         goto end;
 27     }
 28 
 29     name = cJSON_CreateString("Awesome 4K");
 30     if (name == NULL)
 31     {
 32         goto end;
 33     }
 34     /* after creation was successful, immediately add it to the monitor,
 35      * thereby transferring ownership of the pointer to it */
 36     cJSON_AddItemToObject(monitor, "name", name);
 37 
 38     resolutions = cJSON_CreateArray();
 39     if (resolutions == NULL)
 40     {
 41         goto end;
 42     }
 43     cJSON_AddItemToObject(monitor, "resolutions", resolutions);
 44 
 45     for (index = 0; index < (sizeof(resolution_numbers) / (2 * sizeof(int))); ++index)
 46     {
 47         resolution = cJSON_CreateObject();
 48         if (resolution == NULL)
 49         {
 50             goto end;
 51         }
 52         cJSON_AddItemToArray(resolutions, resolution);
 53 
 54         width = cJSON_CreateNumber(resolution_numbers[index][0]);
 55         if (width == NULL)
 56         {
 57             goto end;
 58         }
 59         cJSON_AddItemToObject(resolution, "width", width);
 60 
 61         height = cJSON_CreateNumber(resolution_numbers[index][1]);
 62         if (height == NULL)
 63         {
 64             goto end;
 65         }
 66         cJSON_AddItemToObject(resolution, "height", height);
 67     }
 68 
 69     string = cJSON_Print(monitor);
 70     if (string == NULL)
 71     {
 72         fprintf(stderr, "Failed to print monitor.
");
 73     }
 74 
 75 end:
 76     cJSON_Delete(monitor);
 77     return string;
 78 }
 79 
 80 /* return 1 if the monitor supports full hd, 0 otherwise */
 81 int supports_full_hd(const char * const monitor)
 82 {
 83     const cJSON *resolution = NULL;
 84     const cJSON *resolutions = NULL;
 85     const cJSON *name = NULL;
 86     int status = 0;
 87     cJSON *monitor_json = cJSON_Parse(monitor);
 88     if (monitor_json == NULL)
 89     {
 90         const char *error_ptr = cJSON_GetErrorPtr();
 91         if (error_ptr != NULL)
 92         {
 93             fprintf(stderr, "Error before: %s
", error_ptr);
 94         }
 95         status = 0;
 96         goto end;
 97     }
 98 
 99     name = cJSON_GetObjectItemCaseSensitive(monitor_json, "name");
100     if (cJSON_IsString(name) && (name->valuestring != NULL))
101     {
102         printf("Checking monitor "%s"
", name->valuestring);
103     }
104 
105     resolutions = cJSON_GetObjectItemCaseSensitive(monitor_json, "resolutions");
106     cJSON_ArrayForEach(resolution, resolutions)
107     {
108         cJSON *width = cJSON_GetObjectItemCaseSensitive(resolution, "width");
109         cJSON *height = cJSON_GetObjectItemCaseSensitive(resolution, "height");
110 
111         if (!cJSON_IsNumber(width) || !cJSON_IsNumber(height))
112         {
113             status = 0;
114             goto end;
115         }
116 
117         int w = width->valueint;
118         int h = height->valueint;
119         cout << "(w h) (" << w << " " << h << ")
";
120 
121         if ((width->valuedouble == 1920) && (height->valuedouble == 1080))
122         {
123             status = 1;
124             goto end;
125         }
126     }
127 
128 end:
129     cJSON_Delete(monitor_json);
130     return status;
131 }
132 
133 int main()
134 {
135     char *strJson = create_monitor();
136     cout << strJson << "
";
137     supports_full_hd(strJson);
138     free(strJson);
139     system("pause");
140     return 0;
141 }

另一个json库:jsoncpp github地址：https://github.com/open-source-parsers/jsoncpp