用C语言编写文件复制程序。分别使用系统调用read (fd,buf,nbytes)、write(fd, buf,nbytes)和文件的库函数fread(buf,size,nitems,fp)、fwrite(buf,size,nitems,fp)，编写一个文件复制程序。

使用系统调用read()和write()函数来实现文件复制程序：

#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>

#define BUFFER_SIZE 1024

int main(int argc, char *argv[]) {
    if (argc < 3) {
        fprintf(stderr, "Usage: %s <source> <destination>\n", argv[0]);
        exit(1);
    }

    int source_fd = open(argv[1], O_RDONLY);
    if (source_fd == -1) {
        perror("Failed to open source file");
        exit(1);
    }

    int dest_fd = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
    if (dest_fd == -1) {
        perror("Failed to open destination file");
        exit(1);
    }

    char buffer[BUFFER_SIZE];
    ssize_t bytes_read;

    while ((bytes_read = read(source_fd, buffer, BUFFER_SIZE)) > 0) {
        ssize_t bytes_written = write(dest_fd, buffer, bytes_read);
        if (bytes_written != bytes_read) {
            perror("Write error");
            exit(1);
        }
    }

    if (bytes_read == -1) {
        perror("Read error");
        exit(1);
    }

    if (close(source_fd) == -1) {
        perror("Failed to close source file");
        exit(1);
    }

    if (close(dest_fd) == -1) {
        perror("Failed to close destination file");
        exit(1);
    }

    return 0;
}

使用文件的库函数fread()和fwrite()来实现文件复制程序：

#include <stdio.h>
#include <stdlib.h>

#define BUFFER_SIZE 1024

int main(int argc, char *argv[]) {
    if (argc < 3) {
        fprintf(stderr, "Usage: %s <source> <destination>\n", argv[0]);
        exit(1);
    }

    FILE *source_file = fopen(argv[1], "rb");
    if (source_file == NULL) {
        perror("Failed to open source file");
        exit(1);
    }

    FILE *dest_file = fopen(argv[2], "wb");
    if (dest_file == NULL) {
        perror("Failed to open destination file");
        exit(1);
    }

    char buffer[BUFFER_SIZE];
    size_t items_read;

    while ((items_read = fread(buffer, sizeof(char), BUFFER_SIZE, source_file)) > 0) {
        size_t items_written = fwrite(buffer, sizeof(char), items_read, dest_file);
        if (items_written != items_read) {
            perror("Write error");
            exit(1);
        }
    }

    if (ferror(source_file)) {
        perror("Read error");
        exit(1);
    }

    if (fclose(source_file) != 0) {
        perror("Failed to close source file");
        exit(1);
    }

    if (fclose(dest_file) != 0) {
        perror("Failed to close destination file");
        exit(1);
    }

    return 0;
}