如何在json_tokener_parse()之后获取json值? [英] How to get json values after json_tokener_parse()?

问题描述

我有以下代码

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>

#include <json/json.h>

int main(int argc, char **argv)
{
      json_object *new_obj;
      char buf[] = "{ \"foo\": \"bar\", \"foo2\": \"bar2\", \"foo3\": \"bar3\" }"
      new_obj = json_tokener_parse(buf);
      printf("The value of foo is %s" /*What I have to put here?*/);
      printf("The value of foo2 is %s" /*What I have to put here?*/);
      printf("The value of foo3 is %s" /*What I have to put here?*/);
      json_object_put(new_obj);
}

我知道我们必须使用json_tokener_parse()来解析json字符串，但是我不知道如何从json_object new_obj中提取值，如上面代码中的注释所示

I knwo that we have to use json_tokener_parse() to parse json strings but then I do not know how to extract values from the json_object new_obj as indicated in the comments in the code above

如何在json_tokener_parse()之后获取json值?

How to get json values after json_tokener_parse() ?

推荐答案

首先，您需要将json_object获取到特定节点:

First you need to get the json_object to a specific node:

json_object *obj_foo = json_object_object_get(new_obj, "foo");

...然后，您可以使用适当的getter来获取特定类型的节点的值:

...then you can use the appropriate getter to obtain the value of the node in a specific type:

char *foo_val = json_object_get_string(obj_foo2);

因此，简而言之，您可以这样做:

So, in short, you could do:

printf("The value of foo is %s", 
    json_object_get_string(json_object_object_get(new_obj, "foo"))
);

显然，最好分多个步骤进行操作，以便您可以检查错误(在本例中为空指针)并防止未定义的行为等.

Obviously, it's better to do it in multiple steps so that you can check for errors (in this case: null pointers) and prevent undefined behavior and such.

您可以在此处找到JSON C API文档.

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