my implementation

#include <cstdio>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <cstring>
#include <cstdlib>
#include <string>
#include <iostream>

extern char implementation(char);

using namespace std;


int main(int argc, char *argv[])
{
    char msg[1024];

    int fd[2];

    fd[0] = open(argv[1], O_RDONLY);
    fd[1] = open(argv[2], O_WRONLY);


    while (read(fd[0], msg, 1024) > 0) {
        char output[2];
        output[0] = implementation(msg[0]);
        output[1] = '\0';
        write(fd[1], output, 2);
    }

    return 0;
}