sorry this is not an issue, just a Question, How to change a key value in a file and save it ?

[FahedSabellioglu]

• Describe the feature in as much detail as possible.

• Include sample usage where appropriate.

[FahedSabellioglu]

The major problem is to change a value in a file and save it back, but this did not seem possible, I tried to do it with boost library, but it just corrupts the format when it saves.
I tried to save the data locally and write them back to a file, but how can I organize them since there are repeated keys with different values;

 [{
  Id= 1
  Name = David
},
{
  Id = 2
  Name = Katja
},
{
  Id = 3
  Name = Luka
}]

[nlohmann]

How does the code look like that you tried? What does the error look like?

[FahedSabellioglu]

Sorry, the code might not be that good, I'm a beginner to c++.
I tried to find the user I want and then find the json file and change it and close the file.
this is a function in a class

void Change_status()
	{

		//looking for an attribute to find the username I need
		if (UserName == "xxlea09xx")
		{ // changing the following_status attribute to true
			Following_status = true;
			std::list<Twitter_user> Reference_list;
			std::ifstream in("@CompGlyndwr_Followers.json");
			json File = json::parse(in);
			for (auto Json_Block : File)
			{
				if (Json_Block["screen_name"] == "xxlea09xx")
				{
					Json_Block["/following"_json_pointer] = true;
					in.close();
				}

			}
		}

[FahedSabellioglu]

I tried to follow the documentation in the method used for writing and save the data into a totally different file, but since I couldn't figure out how to separate the blocks, the keys were overwritten.

and I just want to ask is it possible to store the json data in a vector or a list ? just to write it back to the files with changed values.

[FahedSabellioglu]

My Job is to change certain values in a json file:

1- i tried to change the value in a for loop, then I opened the file and found the place of the block and tried to change the files, but the code this did not work at all since it took forever to go through
2- i checked the documentation for how to write, and I followed it but I did not know how to encapsulate each block with a parenthesis, so it just overwrote the data and it did not work.
3- I thought of saving the blocks in a container of like a vector or a list, But according to what I checked that seemed to be impossible.

[nlohmann]

The input from #1398 (comment) seems to be unrelated to #1398 (comment).

[nlohmann]

To answer the question in the title:

• You can change a JSON value by using the operator[]: If your JSON value j is an array of objects, then j[3]["foo"] goes to the 4th element of the array and accesses the value at object key "foo". You can set it to another value by simply j[3]["foo"] = true; or j[3]["foo"] = "bar";.
• JSON values can be stored to a file with myfile << j;.

[nlohmann]

Do you need further help?