JSON(03)C/C++处理JSON

  C/C++处理JSON的开源库有名的有两个libjson与cJSON. 个人认为cJSON更好用些。

把cJSON的例子调试了下.

效果:

   

   

 代码文件:

/***
*desc:通过cJSON来解析 
*/

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

void demo1()
{
    char *out ;
    cJSON *root,*fmt;
    root=cJSON_CreateObject();
    cJSON_AddItemToObject(root, "name", cJSON_CreateString("Jack (\"Bee\") Nimble"));
    cJSON_AddItemToObject(root, "format", fmt=cJSON_CreateObject());
    cJSON_AddStringToObject(fmt,"type",     "rect");
    cJSON_AddNumberToObject(fmt,"width",        1920);
    cJSON_AddNumberToObject(fmt,"height",       1080);
    cJSON_AddFalseToObject (fmt,"interlace");
    cJSON_AddNumberToObject(fmt,"frame rate",   24);

    out=cJSON_Print(root);
    printf("%s\n",out);
    //free(out);
    out=cJSON_Print(fmt);
    printf("%s\n",out);
    free(out);
    
    cJSON *jName = cJSON_GetObjectItem(root,"name");
    printf("name = %s \n",jName->valuestring);
}

void demo2()
{
    char text4[]="{\n       \"Image\": {\n          \"Width\":  800,\n          \"Height\": 600,\n          \"Title\":  \"View from 15th Floor\",\n         \"Thumbnail\": {\n              \"Url\":    \"http:/*www.json.com/image/481989943\",\n              \"Height\": 125,\n              \"Width\":  \"100\"\n           },\n            \"IDs\": [116, 943, 234, 38793]\n       }\n }";
    char *out;cJSON *json;
    
    json=cJSON_Parse(text4);
    if (!json) 
    {
        printf("Error before: [%s]\n",cJSON_GetErrorPtr());}
    else
    {
        cJSON *pImage = cJSON_GetObjectItem(json,"Image");
        printf("Image = %s \n",pImage->valuestring);

        //int  nCount = cJSON_GetArraySize( pImage); 
        //printf("nCount = %d \n",nCount);

        //数组方式 0 
        cJSON * pArrayItem2 = cJSON_GetArrayItem(pImage, 2);
        //  "Title":        "View from 15th Floor",
        printf("2 pArrayItem2->valuestring = %s \n",pArrayItem2->valuestring);


        //数组方式 1 
        int nCount = cJSON_GetArraySize( cJSON_GetObjectItem(pImage,"Thumbnail") ); 
        printf("Thumbnail nCount = %d \n",nCount);

        /*
         "Thumbnail":    {
                    "Url":  "http:/*www.json.com/image/481989943",
        */
        cJSON * pArrayItemUrl= cJSON_GetArrayItem( cJSON_GetObjectItem(pImage,"Thumbnail") , 0);
        printf("Thumbnail Url = %s \n",pArrayItemUrl->valuestring);


        //数组方式 2
        nCount = cJSON_GetArraySize( cJSON_GetObjectItem(pImage,"IDs") ); 
        printf("IDs nCount = %d \n",nCount);

        /*
         "IDs":  [116, 943, 234, 38793]
        */
        cJSON * pArrayItem22 = cJSON_GetArrayItem( cJSON_GetObjectItem(pImage,"IDs") , 2);
        printf("22 IDs valueint 2= %d \n",pArrayItem22->valueint);

        //数组方式 4 
        cJSON *tasklist=cJSON_GetObjectItem(pImage,"Thumbnail")->child;//子对象 //IDs
        /*
         "root":[{
        "value":"2011-03-17 11:15 - xxxx - xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
        "id":"XXXX_20110315000"
        */
        while(tasklist!=NULL)
        {
            //printf("%s\n",cJSON_GetObjectItem(tasklist,"value")->valuestring);
            tasklist=tasklist->next;
        }

        //数组方式 5 
          nCount = cJSON_GetArraySize( pImage); 
         //cJSON *pArrayItem; 
         //for(int i= 0; i < nCount; i++)
         //{
            //cJSON_Print( cJSON_GetArrayItem(pImage, i));
            //cJSON_Print( pArrayItem);
         //}

        out=cJSON_Print(json);
        cJSON_Delete(json);
        printf("\n ------------\n %s\n",out);
        free(out);
    }
}


int main(void)
{
    printf("------------\n ");
    printf("构建JSON\n ");
    printf("------------\n \n");
    demo1();

    printf("\n------------\n");
    printf("解析JSON\n");
    printf("------------\n");
    demo2();
    return 0;
}