使用cJSON读取JSON数组 [英] Using cJSON to read in a JSON array

问题描述

我正在尝试使用Dave Gamble编写的cJSON库来读取以下JSON数组:

I am attempting to use the cJSON library, written by Dave Gamble, to read in the following JSON array:

"items": 
[
    {
        "name": "command",
        "index": "X",
        "optional": "0"
    },
    {
        "name": "status",
        "index": "X",
        "optional": "0"
    }
]

通过阅读他的文档，我找到了单独阅读的方法对象，但是没有关于数组的任何知识，我无法从给出的示例中推测出如何做到这一点.

From reading his documentation, I found ways to read in individual Objects, but nothing regarding Arrays, and I wasn't able to surmise how to do it from the examples given.

这就是我要尝试的:

cJSON* request_json = NULL;
cJSON* items = cJSON_CreateArray();
cJSON* name = NULL;
cJSON* index = NULL;
cJSON* optional = NULL;

request_json = cJSON_Parse(request_body);

items = cJSON_GetObjectItem(request_json, "items");

name = cJSON_GetObjectItem(items, "name");
index = cJSON_GetObjectItem(items, "index");
optional = cJSON_GetObjectItem(items, "optional");

我知道这是错误的，不仅仅是因为它不起作用，而且我不知道该怎么做.

I know this is wrong, and not just because it's not working, but I can't figure out how to make it right.

显然，我需要循环读取数组每个索引的所有条目的过程.我不知道该怎么做，因为我不知道在代码中应该在哪里使用索引，或者甚至是正确的开始.有一个cJSON_GetArrayItem()，但是它只需要一个数字(可能是一个索引)，而没有字符串来指示它想要的字段.

Obviously I'm going to need to loop the process of reading in all of the entries for each index of the array. I have no idea how I'm going to do that though, because I don't know where I should be using the indexes in this code, or if it is even the right start. There is a cJSON_GetArrayItem(), but it takes only a number (presumably an index) and no string to indicate which field it wants.

推荐答案

文档中提到了parse_object().

Document mentions about parse_object().

我认为这是您需要做的.

I think this is what you need to do.

void parse_object(cJSON *root)
{
  cJSON* name = NULL;
  cJSON* index = NULL;
  cJSON* optional = NULL;

  int i;

  cJSON *item = cJSON_GetObjectItem(items,"items");
  for (i = 0 ; i < cJSON_GetArraySize(item) ; i++)
  {
     cJSON * subitem = cJSON_GetArrayItem(item, i);
     name = cJSON_GetObjectItem(subitem, "name");
     index = cJSON_GetObjectItem(subitem, "index");
     optional = cJSON_GetObjectItem(subitem, "optional"); 
  }
}

将此函数称为

request_json = cJSON_Parse(request_body);
parse_object(request_json);

这篇关于使用cJSON读取JSON数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！