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
        }
    ]
}

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

using namespace std;

//create a monitor with a list of supported resolutions
//NOTE: Returns a heap allocated string, you are required to free it after use.
char *create_monitor(void)
{
    const unsigned int resolution_numbers[3][2] = {
        {1280, 720},
        {1920, 1080},
        {3840, 2160}
    };
    char *string = NULL;
    cJSON *name = NULL;
    cJSON *resolutions = NULL;
    cJSON *resolution = NULL;
    cJSON *width = NULL;
    cJSON *height = NULL;
    size_t index = 0;

    cJSON *monitor = cJSON_CreateObject();
    if (monitor == NULL)
    {
        goto end;
    }

    name = cJSON_CreateString("Awesome 4K");
    if (name == NULL)
    {
        goto end;
    }
    /* after creation was successful, immediately add it to the monitor,
     * thereby transferring ownership of the pointer to it */
    cJSON_AddItemToObject(monitor, "name", name);

    resolutions = cJSON_CreateArray();
    if (resolutions == NULL)
    {
        goto end;
    }
    cJSON_AddItemToObject(monitor, "resolutions", resolutions);

    for (index = 0; index < (sizeof(resolution_numbers) / (2 * sizeof(int))); ++index)
    {
        resolution = cJSON_CreateObject();
        if (resolution == NULL)
        {
            goto end;
        }
        cJSON_AddItemToArray(resolutions, resolution);

        width = cJSON_CreateNumber(resolution_numbers[index][0]);
        if (width == NULL)
        {
            goto end;
        }
        cJSON_AddItemToObject(resolution, "width", width);

        height = cJSON_CreateNumber(resolution_numbers[index][1]);
        if (height == NULL)
        {
            goto end;
        }
        cJSON_AddItemToObject(resolution, "height", height);
    }

    string = cJSON_Print(monitor);
    if (string == NULL)
    {
        fprintf(stderr, "Failed to print monitor.
");
    }

end:
    cJSON_Delete(monitor);
    return string;
}

/* return 1 if the monitor supports full hd, 0 otherwise */
int supports_full_hd(const char * const monitor)
{
    const cJSON *resolution = NULL;
    const cJSON *resolutions = NULL;
    const cJSON *name = NULL;
    int status = 0;
    cJSON *monitor_json = cJSON_Parse(monitor);
    if (monitor_json == NULL)
    {
        const char *error_ptr = cJSON_GetErrorPtr();
        if (error_ptr != NULL)
        {
            fprintf(stderr, "Error before: %s
", error_ptr);
        }
        status = 0;
        goto end;
    }

    name = cJSON_GetObjectItemCaseSensitive(monitor_json, "name");
    if (cJSON_IsString(name) && (name->valuestring != NULL))
    {
        printf("Checking monitor "%s"
", name->valuestring);
    }

    resolutions = cJSON_GetObjectItemCaseSensitive(monitor_json, "resolutions");
    cJSON_ArrayForEach(resolution, resolutions)
    {
        cJSON *width = cJSON_GetObjectItemCaseSensitive(resolution, "width");
        cJSON *height = cJSON_GetObjectItemCaseSensitive(resolution, "height");

        if (!cJSON_IsNumber(width) || !cJSON_IsNumber(height))
        {
            status = 0;
            goto end;
        }

        int w = width->valueint;
        int h = height->valueint;
        cout << "(w h) (" << w << " " << h << ")
";

        if ((width->valuedouble == 1920) && (height->valuedouble == 1080))
        {
            status = 1;
            goto end;
        }
    }

end:
    cJSON_Delete(monitor_json);
    return status;
}

int main()
{
    char *strJson = create_monitor();
    cout << strJson << "
";
    supports_full_hd(strJson);
    free(strJson);
    system("pause");
    return 0;
}

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