如何创建自己的ostream/streambuf？

#include<iostream>
#include <streambuf>
#include<ostream>

class CustomStreambuf : public std::streambuf {
public:
    CustomStreambuf(char* buffer, size_t size) {
        setp(buffer, buffer + size);
    }

    int_type overflow(int_type ch) override {
        if (ch != EOF) {
            *pptr() = ch;
            pbump(1);
            return ch;
        }
        return EOF;
    }
};

class CustomOstream : public std::ostream {
public:
    CustomOstream(char* buffer, size_t size)
        : std::ostream(new CustomStreambuf(buffer, size))
        , streambuf_(rdbuf()) {}

    ~CustomOstream() {
        delete rdbuf();
    }

private:
    CustomStreambuf* streambuf_;
};

int main() {
    char buffer[1024];
    CustomOstream custom_ostream(buffer, sizeof(buffer));

    custom_ostream << "Hello, World!"<< std::endl;
    std::cout << "Custom output: "<< buffer<< std::endl;

    return 0;
}