how can I send commands(like COM_REGISTER_SLAVE or COM_BINLOG_DUMP) to the mysql master using C++?

I referred to a python program about this function, but I can't understand how it works. In my opinion, it just sends the packet to a connection which is from 'pymysql.connect'. How can I realize this function using C++;

self._stream_connection.wfile.write(packet)
#the packet is data which maintains the payload

I did some attempts as follow:

// slave.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//
#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <string>
#include <string.h>

#include <sys/socket.h>
/*
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/shm.h>
*/
#include <mysql_connection.h>
#include <cppconn/driver.h>
#include <cppconn/exception.h>
#include <cppconn/resultset.h>
#include <cppconn/statement.h>
#include <cppconn/prepared_statement.h>
using namespace sql;
using namespace std;
#define DBHOST "tcp://0.0.0.0:3306"
#define USER "slave1"
#define PASSWORD "125555"

typedef unsigned char BYTE;

struct Payload {
    BYTE cmd[1];//default 12 COM_BINLOG_DUMP
    BYTE bpos[4];//
    BYTE flag[2];//0
    BYTE s_id[4];//1
    BYTE bfile[16]; //mysql - bin.000002
};

void intTobyte(BYTE bytes[], int n, int len) {
    for (int i = 0; i < len; i++) {
        bytes[i] = n & 0x000000ff << 8*i;
    }
}

void stringTobyte(BYTE bytes[], string str, int len) {
    char chs[50];
    strcpy(chs, str.c_str());
    for (int i = 0; i < len; i++) {
        bytes[i] = (int)chs[i] & 0x000000ff << 8 * 0;
    }
}

int main() {

    Driver* driver;
    Connection* conn;
    Statement *state;
    ResultSet* result;
    driver = get_driver_instance();
    conn = driver->connect(DBHOST, USER, PASSWORD);
    string binlog_file;
    int binlog_pos;
    struct Payload *payload;

    state = conn->createStatement();
    result = state->executeQuery("show master status;");
    while (result->next() != NULL)
    {
        binlog_file = result->getString("File");
        binlog_pos = result->getInt("Position");
        cout << binlog_file << endl << binlog_pos << endl;
    }
    intTobyte(payload->cmd, 12, 1);
    intTobyte(payload->bpos,binlog_pos,4);
    intTobyte(payload->flag, 0, 2);
    intTobyte(payload->s_id, 1, 4);
    stringTobyte(payload->bfile, binlog_file, binlog_file.length());

    printf("%0x\n", payload->cmd[0]);
    printf("%0x %0x %0x %0x\n", payload->bpos[0], payload->bpos[1], payload->bpos[2], payload->bpos[3]);
    //printf("%0x %0x %0x %0x\n", payload.s_id[0], payload.s_id[1], payload.s_id[2], payload.s_id[3]);
    //printf("%0x %0x %0x %0x\n", payload.bfile[0], payload.bfile[1], payload.bfile[2], payload.bfile[3]);

    send((socket)conn, (char*)payload, 27, 0);//this sentence goes wrong.

    delete conn;
    driver = NULL;
    conn = NULL;
    return 0;
}

this is the error information from g++:

register_slave.cpp:87:42: error: invalid conversion from ‘int (*)(int, int, int) throw ()’ to ‘int’ [-fpermissive]
  send((socket)conn, (char*)payload, 27, 0);

If you have any good thoughts about this question, please leave your comments, thanks in advance. Or if you have some advices, please let me know as well.