C语言open函数的使用例子

吐槽

都已经大二了，老师既然还教我们C语言的基础open函数的使用，感到无力！！！只能粤嵌牛逼

要求

作业1：尝试从文件中读取某些字节？ test.txt
作业2： test.txt，如果该文件存在则清空，不存在则创建，写入"hello"
作业3： 完成copy.c的拷贝 例如： ./copy 1.txt 2.txt

//
// Created by 90822 on 2020/5/7.
//
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>

#define BUFFER_MAX  1024

int fd1 = 0, fd2 = 0;
int wt1 = 0;
int size1 = 0, size2 = 0;
char buffer1[] = {} ,buffer2[] = {} ;

int work1(char *path);
int work2(char *path);
int work3(char *path1, char *path2);


int main(int argc, char* argv[]){
    char *path1 = "../test1.txt";
    char *path2 = "../test2.txt";
    work1(path1);   //作业1
    work2(path2);  //作业2
    work3(path1, path2);//作业3


    return 0;

}


int work1(char *path) {
    printf("\n作业要求一\n");

    if ((fd1 = open(path, O_RDONLY)) < 0) {
        printf("你的test1.txt文件出现错误！");
        exit(-1);
    } else {
        printf("文件描述符为：%d\n", fd1);
    }

    if ((size1 = read(fd1, buffer1, BUFFER_MAX)) < 0) {
        printf("文件读取失败，请检查文件！\n");
        exit(-1);
    } else {
        printf("文件内容为：%s\n", buffer1);
        close(fd1);

    }

    printf("******************************************************************\n");
}

int work2(char *path){
    printf("\n作业要求二\n");
    char buf[] = "靓仔";

    if((fd2 = open(path, O_WRONLY | O_CREAT | O_TRUNC)) < 0 && (size2 = read(fd2, buffer2, BUFFER_MAX)) < 0){
        printf("你的test1.txt文件出现错误！");
        exit(-1);
    } else {
        printf("源文件内容为：%s\n", buffer2);
        if((wt1 = write(fd2, buf, sizeof(buf)))>0){
            printf("写入了: %d个字节\n",wt1 );
            printf("文件描述符为：%d\n", fd2);
            close(fd2);
        }else
        {
            printf("文件写入失败\n");
            exit(-1);
        }
    }

    if((fd2 =(open(path,  O_RDONLY))) < 0 ) {
        printf("你的test1.txt文件出现错误！");
        exit(-1);
    }else{
        if ((size2 = read(fd2, buffer2, BUFFER_MAX)) < 0) {
            printf("读取操作的size2： %d\n", size2);
            printf("文件读取失败，请检查文件！\n");
            exit(-1);
        } else {
            printf("文件内容为：%s\n", buffer2);
            close(fd2);
        }
    }
    printf("****************************************************************\n");
}



int work3(char * path1, char * path2){
    printf("\n作业要求三\n");

    if((fd1 = open(path1, O_RDWR)) > 0 && (size1 = read(fd1, buffer1, BUFFER_MAX)) > 0){
        printf("拷贝的目标文件内容：%s\n", buffer1);
        close(fd1);
    }else{
        printf("打开或者读取文件失败，请检查\n");
        exit(-1);
    }


    if((fd2 = open(path2, O_RDWR)) > 0 &&  (size2 = read(fd2, buffer2, BUFFER_MAX)) > 0){
        printf("拷贝前的源文件内容：%s\n", buffer2);


        if((wt1 = write(fd2,buffer1,size1)) > 0){
            printf("写入中...\n");
            printf("一共写入了: %d个字节\n",wt1 );
            close(fd2);

        }else{
            printf("文件写入失败！\n");
            exit(-1);
        }

        if((fd2 =(open(path2,  O_RDONLY))) < 0 ) {
            printf("你的test1.txt文件出现错误！");
            exit(-1);
        }else{
            if ((size2 = read(fd2, buffer2, BUFFER_MAX)) < 0) {
                printf("文件读取失败，请检查文件！\n");
                exit(-1);
            } else {
                printf("拷贝后test1文件内容为：%s\n", buffer2);
                close(fd2);
            }
        }




    }else{
        printf("打开或者读取文件失败，请检查\n");
        exit(-1);
    }


}