Write some JSON using a rapidjson library

rapidjson_gen_json.cpp

#ifdef SHELL
g++ -Wall -Werror -g -I../../cclib/rapidjson/include $0 && ./a.out
exit 0
#endif

// Output is:
// {"project":"rapidjson","stars":11}
// {"Name":"XYZ","Rollnumer":2,"array":["hello","world"],"Marks":{"Math":"50","Science":"70","English":"50","Social Science":"70"}}
// {"FromEmail":"sender@gmail.com","FromName":"Sender's name","Subject":"My subject","Recipients":[{"Email":"recipient@gmail.com"}],"Text-part":"this is my text"}


#include "rapidjson/document.h"
#include "rapidjson/writer.h"
#include "rapidjson/stringbuffer.h"
#include <iostream>

using namespace rapidjson;

// https://github.com/miloyip/rapidjson#usage-at-a-glance
void sample_basic() {
	// 1. Parse a JSON string into DOM.
    const char* json = "{\"project\":\"rapidjson\",\"stars\":10}";
    Document d;
    d.Parse(json);

    // 2. Modify it by DOM.
    Value& s = d["stars"];
    s.SetInt(s.GetInt() + 1);

    // 3. Stringify the DOM
    StringBuffer buffer;
    Writer<StringBuffer> writer(buffer);
    d.Accept(writer);

    // Output {"project":"rapidjson","stars":11}
    std::cout << buffer.GetString() << std::endl;
}

void sample_other() {
		// document is the root of a json message
	rapidjson::Document document;
 
	// define the document as an object rather than an array
	document.SetObject();
 
	// create a rapidjson array type with similar syntax to std::vector
	rapidjson::Value array(rapidjson::kArrayType);
 
	// must pass an allocator when the object may need to allocate memory
	rapidjson::Document::AllocatorType& allocator = document.GetAllocator();
 
	// chain methods as rapidjson provides a fluent interface when modifying its objects
	array.PushBack("hello", allocator).PushBack("world", allocator);//"array":["hello","world"]
 
	document.AddMember("Name", "XYZ", allocator);
	document.AddMember("Rollnumer", 2, allocator);
	document.AddMember("array", array, allocator);
 
	// create a rapidjson object type
	rapidjson::Value object(rapidjson::kObjectType);
	object.AddMember("Math", "50", allocator);
	object.AddMember("Science", "70", allocator);
	object.AddMember("English", "50", allocator);
	object.AddMember("Social Science", "70", allocator);
	document.AddMember("Marks", object, allocator);
	//	fromScratch["object"]["hello"] = "Yourname";
 
	StringBuffer strbuf;
	Writer<StringBuffer> writer(strbuf);
	document.Accept(writer);

	std::cout << strbuf.GetString() << std::endl;
}

void sample_sendapi() {
	Document d;
	Document::AllocatorType& alloc = d.GetAllocator();

	std::string mytext = "this is my text";

	d.SetObject();

	d.AddMember("FromEmail", "sender@gmail.com", alloc);
	d.AddMember("FromName", "Sender's name", alloc);
	d.AddMember("Subject", "My subject", alloc);


	{
		Value recipients(kArrayType);
		
		{	
			Value recipient(kObjectType);
			recipient.AddMember("Email", "recipient@gmail.com", alloc);
			recipients.PushBack(recipient, alloc);
		}

		d.AddMember("Recipients", recipients, alloc);
	}

	{
		Value textPart;
		textPart.SetString(mytext.c_str(), alloc);
		d.AddMember("Text-part", textPart, alloc);
	}

	StringBuffer buffer;
    Writer<StringBuffer> writer(buffer);
    d.Accept(writer);

	std::cout << buffer.GetString() << std::endl;
}

int main() {
	sample_basic();

	sample_other();

	sample_sendapi();

    return 0;
}