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函数的文件复制程序：

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

#define BUFFER_SIZE 1024

int main(int argc, char *argv[]) {
    int source_file = open(argv[1], O_RDONLY);
    if (source_file == -1) {
        perror("Failed to open source file");
        return 1;
    }

    int dest_file = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, 0644);
    if (dest_file == -1) {
        perror("Failed to create destination file");
        return 1;
    }

    char buffer[BUFFER_SIZE];
    ssize_t read_bytes;
    while ((read_bytes = read(source_file, buffer, BUFFER_SIZE)) > 0) {
        ssize_t written_bytes = write(dest_file, buffer, read_bytes);
        if (written_bytes != read_bytes) {
            perror("Failed to write to destination file");
            return 1;
        }
    }

    if (read_bytes < 0) {
        perror("Failed to read from source file");
        return 1;
    }

    close(source_file);
    close(dest_file);

    return 0;
}

使用文件的库函数fread和fwrite函数的文件复制程序：

#include <stdio.h>

#define BUFFER_SIZE 1024

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

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

    char buffer[BUFFER_SIZE];
    size_t read_items;
    while ((read_items = fread(buffer, 1, BUFFER_SIZE, source_file)) > 0) {
        size_t written_items = fwrite(buffer, 1, read_items, dest_file);
        if (written_items != read_items) {
            perror("Failed to write to destination file");
            return 1;
        }
    }

    if (ferror(source_file)) {
        perror("Failed to read from source file");
        return 1;
    }

    fclose(source_file);
    fclose(dest_file);

    return 0;
}