如何使用整数作为键/名称将成员添加到rapidjson文档？ [英] How can I add members to a rapidjson document using integers as the key/name?

问题描述

我使用for循环，并希望使用迭代器，i，作为键/名称当我添加一个成员到文档。例如，我想让文档看起来像这样：

{1：123.321，2：456.654}

这是我到目前为止所尝试的。

1。将i转换为const char *

  rapidjson :: Value newDouble（6）; 
 for（int i = 0; i< laserScan.size（）; i ++）{
 newDouble.SetDouble（laserScan [i]）; 
 const char * index = std :: to_string（i）.c_str（）; 
 d.AddMember（index，newDouble，d.GetAllocator（））; 
} 
  

这会产生编译器错误，告诉我AddMember只能接受类型rapidjson的参数:: GenericValue&：

 错误：没有匹配的函数调用'rapidjson :: GenericDocument< rapidjson :: UTF8& > :: AddMember（const char *& rapidjson :: Value& rapidjson :: MemoryPoolAllocator<&）'
 d.AddMember（index，newDouble，d.GetAllocator（））;将此名称 - 值对添加到JSON字符串
  

2。使用rapidjson类型将i转换为字符串

  rapidjson :: Value newDouble（6），newStringIndex 
 for（int i = 0; i< laserScan.size（）; i ++）{
 newDouble.SetDouble（laserScan [i]）; 
 const char * index = std :: to_string（i）.c_str（）; 
 size =（rapidjson :: SizeType）std :: strlen（index）; 
 newStringIndexSetString（rapidjson :: StringRef（index，size））; 
 d.AddMember（newStringIndex，newDouble，d.GetAllocator（））; 
} 
  

这会从Writer类抛出以下运行时错误：

 断言`！hasRoot_'失败。 
  

为什么我困惑

$

  d.AddMember（ 1，newDouble，d.GetAllocator（））; 
  

当我尝试它时，这是工作，但我不知道为什么将整数转换为const char *不会。

解决方案

我发现了一个解决方法。而不是使所有的键整数，我只是添加关键索引与相应的值是所有索引的数组。然后我添加了另一个名为data的数组，其中包含所有数据的数组：

  rapidjson :: Document document; 
 rapidjson :: Document :: AllocatorType& allocator = document.GetAllocator（）; 
 rapidjson :: Value dataArray（rapidjson :: kArrayType），; 
 
 for（int i = 0; i  dataArray.PushBack（rapidjson :: Value（）。SetDouble（laserScan [i]），allocator ）; 
} 
 document.AddMember（data，dataArrary，allocator）; 
  

I'm using a for loop and want to use the iterator, i, as the key/name when I add a member to the document. For example I want the document to look like this:

{"1":"123.321","2":"456.654"}

Here is what I have tried so far.

1. Converting i to a const char*

rapidjson::Value newDouble(6);
for(int i = 0;i<laserScan.size();i++){
    newDouble.SetDouble(laserScan[i]);
    const char* index = std::to_string(i).c_str();
    d.AddMember(index,newDouble,d.GetAllocator());
}

This generates a compiler error telling me that AddMember can only take arguments of type rapidjson::GenericValue&:

error: no matching function for call to ‘rapidjson::GenericDocument<rapidjson::UTF8<> >::AddMember(const char*&, rapidjson::Value&, rapidjson::MemoryPoolAllocator<>&)’
     d.AddMember(index,newDouble,d.GetAllocator());//add this name-value pair to the JSON string

2. Converting i to a string using rapidjson types

rapidjson::Value newDouble(6), newStringIndex(5);
for(int i = 0;i<laserScan.size();i++){    
    newDouble.SetDouble(laserScan[i]);
    const char* index = std::to_string(i).c_str();
    size = (rapidjson::SizeType)std::strlen(index);
    newStringIndex.SetString(rapidjson::StringRef(index,size));
    d.AddMember(newStringIndex,newDouble,d.GetAllocator());
}

This throws the following run-time error from Writer class:

Assertion `!hasRoot_' failed.

Why I'm Confused

Shouldn't solution #1 be the same thing as doing the following?

d.AddMember("1",newDouble,d.GetAllocator());    

This works when I try it, but I can't figure out why converting an integer to a const char* won't.

解决方案

I found a workaround. Instead of making all the keys integers, I just added the key "indices" with the corresponding value being an array of all the indices. Then I added another array called "data" which contained an array of all the data:

rapidjson::Document document;
rapidjson::Document::AllocatorType& allocator = document.GetAllocator();
rapidjson::Value dataArray(rapidjson::kArrayType), ;

for(int i = 0;i<laserScan.size();i++){                 
    dataArray.PushBack(rapidjson::Value().SetDouble(laserScan[i]),allocator);
}
document.AddMember("data",dataArrary,allocator);

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