純C/C++ 存取JSON(使用cJSON函式庫)

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資料來源: http://sourceforge.net/projects/cjson/

json官方介绍: https://www.json.org/json-zh.html
cJSON github地址: https://github.com/DaveGamble/cJSON

 

範例程式

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "cJSON.h"

char * create1()

{

     cJSON *root,*dir1,*dir2,*dir3;

     char *out;

     // 創建json陣列型結構體

     root = cJSON_CreateArray();

     // 為陣列添加物件

     cJSON_AddItemToArray(root,dir1=cJSON_CreateObject());

     // 為物件添加字串鍵值對

     cJSON_AddStringToObject(dir1,"name",".");

     cJSON_AddStringToObject(dir1,"path","uploads/");

     cJSON_AddStringToObject(dir1,"flag","true");

     cJSON_AddItemToArray(root,dir2=cJSON_CreateObject());

     cJSON_AddStringToObject(dir2,"name","..");

     cJSON_AddStringToObject(dir2,"path","uploads");

     cJSON_AddStringToObject(dir2,"flag","true");

     cJSON_AddItemToArray(root,dir3=cJSON_CreateObject());

     cJSON_AddStringToObject(dir3,"name","wang.txt");

     cJSON_AddStringToObject(dir3,"path","uploads/wang.txt");

     cJSON_AddStringToObject(dir3,"flag","false");

     // 將json結構體轉換為字串

     out=cJSON_Print(root);

     // 刪除

     cJSON_Delete(root);

     return out;

}

 

char * create2()

{

     cJSON *root,*dir,*subdir,*dir1,*dir2,*dir3;

     char *out;

     root=cJSON_CreateObject();

 

     cJSON_AddItemToObject(root,"Root",dir=cJSON_CreateObject());

     cJSON_AddStringToObject(dir,"name","/");

     cJSON_AddStringToObject(dir,"path","/");

     cJSON_AddStringToObject(dir,"flag","true");

 

     cJSON_AddItemToObject(root,"Child",subdir = cJSON_CreateArray());

     cJSON_AddItemToObject(subdir,"dira",dir1=cJSON_CreateObject());

     cJSON_AddStringToObject(dir1,"name",".");

     cJSON_AddStringToObject(dir1,"path","/./");

     cJSON_AddStringToObject(dir1,"flag","true");

     cJSON_AddItemToObject(subdir,"dira",dir2=cJSON_CreateObject());

     cJSON_AddStringToObject(dir2,"name","..");

     cJSON_AddStringToObject(dir2,"path","/../");

     cJSON_AddStringToObject(dir2,"flag","true");

     cJSON_AddItemToObject(subdir,"dira",dir3=cJSON_CreateObject());

     cJSON_AddStringToObject(dir3,"name","uploads");

     cJSON_AddStringToObject(dir3,"path","/uploads/");

     cJSON_AddStringToObject(dir3,"flag","true");

 

     out=cJSON_Print(root);

     cJSON_Delete(root);

     return out;

}

 

 

char * create3()

{

     cJSON *root,*img,*thm;

     char *out;

     int nums[4]={100,200,300,400};

     root=cJSON_CreateObject();

     cJSON_AddItemToObject(root, "Root", img=cJSON_CreateObject());

     cJSON_AddNumberToObject(img,"key",800);

     cJSON_AddNumberToObject(img,"value",600);

     cJSON_AddStringToObject(img,"Title","Sugon");

     cJSON_AddItemToObject(img,"child",thm=cJSON_CreateObject());

     cJSON_AddNumberToObject(thm,"key",125);

     cJSON_AddStringToObject(thm,"value","100");

         cJSON_AddStringToObject(thm,"Url","www.sugon.com");

     cJSON_AddItemToObject(img,"nums", cJSON_CreateIntArray(nums,4));

     out=cJSON_Print(root);

     cJSON_Delete(root);

     return out;

}

 

char * create4()

{

     cJSON *root,*dir1,*dir2;

     char *out;

     const char *ro = "Root";

     root=cJSON_CreateObject();

     cJSON_AddItemToObject(root,ro,dir1=cJSON_CreateArray());

     cJSON_AddNumberToObject(dir1,"key",800);

     cJSON_AddNumberToObject(dir1,"value",600);

     cJSON_AddStringToObject(dir1,"Title","key and value");

     cJSON_AddItemToObject(root,ro,dir2=cJSON_CreateArray());

     cJSON_AddNumberToObject(dir2,"value",125);

     cJSON_AddStringToObject(dir2,"key","100");

     cJSON_AddStringToObject(dir2,"Title","value and key");

     out=cJSON_Print(root);

     cJSON_Delete(root);

     return out;

}

 

void parse1(char *out)

{

     cJSON * root,*arrayItem,*item,*name,*path,*flag;

     int i = 0,size = 0;

     char *pr = NULL,*na = NULL,*pa = NULL,*fl = NULL;

 

     // 將字串解析成json結構體

     root = cJSON_Parse(out);

     // 根據結構體獲取陣列大小

     size = cJSON_GetArraySize(root);

     //printf("%d\n",size);

     // 遍歷數組

     for(i=0;i<size;i++)

     {

         //獲取第i個陣列項

         arrayItem = cJSON_GetArrayItem(root,i);

         if(arrayItem)

         {

              //printf("%s\n","start......");

              //講json結構體轉換成字串

              pr = cJSON_Print(arrayItem);

              item = cJSON_Parse(pr);

              name = cJSON_GetObjectItem(item,"name");

              path = cJSON_GetObjectItem(item,"path");

              flag = cJSON_GetObjectItem(item,"flag");

              na = cJSON_Print(name);

              pa = cJSON_Print(path);

              fl = cJSON_Print(flag);

              //printf("%s\n",pr);

              printf("name:%s\n",na);

              printf("path:%s\n",pa);

              printf("flag:%s\n\n",fl);

         }

     }

}

 

void parse2(char *out)

{

     cJSON * root,*Root,*Child,*arrayItem,*item,*name,*path,*flag;

     int i = 0,size = 0;

     char *pr = NULL,*na = NULL,*pa = NULL,*fl = NULL;

     root = cJSON_Parse(out);

     if(root)

     {

         Root = cJSON_GetObjectItem(root,"Root");

         if(Root)

         {

              name = cJSON_GetObjectItem(Root,"name");

              path = cJSON_GetObjectItem(Root,"path");

              flag = cJSON_GetObjectItem(Root,"flag");

              na = cJSON_Print(name);

              pa = cJSON_Print(path);

              fl = cJSON_Print(flag);

              printf("Root:\n");

              printf("name:%s\n",na);

              printf("path:%s\n",pa);

              printf("flag:%s\n\n",fl);

         }

         Child = cJSON_GetObjectItem(root,"Child");

         if(Child)

         {

              size = cJSON_GetArraySize(Child);

              //printf("%d\n",size);

              printf("Child:\n");

              for(i=0;i<size;i++)

              {

                   arrayItem = cJSON_GetArrayItem(Child,i);

                   if(arrayItem)

                   {

                       //printf("%s\n","start......");

                       pr = cJSON_Print(arrayItem);

                       item = cJSON_Parse(pr);

                       name = cJSON_GetObjectItem(item,"name");

                       path = cJSON_GetObjectItem(item,"path");

                       flag = cJSON_GetObjectItem(item,"flag");

                       na = cJSON_Print(name);

                       pa = cJSON_Print(path);

                       fl = cJSON_Print(flag);

                       //printf("%s\n",pr);

                       printf("name:%s\n",na);

                       printf("path:%s\n",pa);

                       printf("flag:%s\n\n",fl);

                   }

              }

         }

     }

}

 

int main()
{

     char *out1 = create1();

     char *out2 = create2();

     char *out3 = create3();

     char *out4 = create4();

     printf("%s\n\n\n",out1);

     parse1(out1);

     printf("%s\n\n\n",out2);

     parse2(out2);

     printf("%s\n\n\n",out3);

     printf("%s\n\n\n",out4);

     return 0;

}

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