将std :: cout重定向到自定义编写器

#include<iostream>
#include <streambuf>

class CustomWriter : public std::streambuf {
public:
    CustomWriter() {
        setp(buffer, buffer + sizeof(buffer) - 1);
    }

    int overflow(int c) override {
        if (c != EOF) {
            *pptr() = c;
            pbump(1);
            sync();
        }
        return 0;
    }

    int sync() override {
        std::cout << "Custom output: "<< std::string(pbase(), pptr())<< std::endl;
        setp(buffer, buffer + sizeof(buffer) - 1);
        return 0;
    }

private:
    char buffer[1024];
};

int main() {
    CustomWriter writer;
    std::streambuf *oldCoutBuffer = std::cout.rdbuf(&writer);

    std::cout << "Hello, world!"<< std::endl;

    std::cout.rdbuf(oldCoutBuffer);
    return 0;
}