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的文件复制程序：

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

#define BUFSIZE 1024

int main(int argc, char *argv[]) {
    if (argc != 3) {
        printf("usage: %s <source> <destination>\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    int in_fd, out_fd;
    char buffer[BUFSIZE];
    ssize_t bytes_read;

    // 打开源文件
    in_fd = open(argv[1], O_RDONLY);
    if (in_fd == -1) {
        perror("open");
        exit(EXIT_FAILURE);
    }

    // 创建目标文件
    out_fd = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
    if (out_fd == -1) {
        perror("open");
        exit(EXIT_FAILURE);
    }

    // 读取源文件并写入目标文件
    while ((bytes_read = read(in_fd, buffer, BUFSIZE)) > 0) {
        if (write(out_fd, buffer, bytes_read) != bytes_read) {
            perror("write");
            exit(EXIT_FAILURE);
        }
    }

    if (bytes_read == -1) {
        perror("read");
        exit(EXIT_FAILURE);
    }

    // 关闭文件
    if (close(in_fd) == -1) {
        perror("close");
        exit(EXIT_FAILURE);
    }

    if (close(out_fd) == -1) {
        perror("close");
        exit(EXIT_FAILURE);
    }

    return 0;
}

使用文件的库函数fread和fwrite的文件复制程序：

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

#define BUFSIZE 1024

int main(int argc, char *argv[]) {
    if (argc != 3) {
        printf("usage: %s <source> <destination>\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    FILE *in_fp, *out_fp;
    char buffer[BUFSIZE];
    size_t bytes_read;

    // 打开源文件
    in_fp = fopen(argv[1], "rb");
    if (in_fp == NULL) {
        perror("fopen");
        exit(EXIT_FAILURE);
    }

    // 创建目标文件
    out_fp = fopen(argv[2], "wb");
    if (out_fp == NULL) {
        perror("fopen");
        exit(EXIT_FAILURE);
    }

    // 读取源文件并写入目标文件
    while ((bytes_read = fread(buffer, 1, BUFSIZE, in_fp)) > 0) {
        if (fwrite(buffer, 1, bytes_read, out_fp) != bytes_read) {
            perror("fwrite");
            exit(EXIT_FAILURE);
        }
    }

    if (ferror(in_fp)) {
        perror("fread");
        exit(EXIT_FAILURE);
    }

    // 关闭文件
    if (fclose(in_fp) != 0) {
        perror("fclose");
        exit(EXIT_FAILURE);
    }

    if (fclose(out_fp) != 0) {
        perror("fclose");
        exit(EXIT_FAILURE);
    }

    return 0;
}