Linux 文件读写

1、最基础的读写函数

 open()
 read()
 write()
 需要的头文件：
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <iostream>
#include <string.h>
#include <stdio.h>
using namespace std;

int main()
{
        /*write()函数*/
        int fd = open("/data/joyyzhang/mypro/a",
                       O_CREAT|O_WRONLY|O_TRUNC);
        const char *buff = "This is an io test !!!\n";
        ssize_t nr;

        nr = write(fd,buff,strlen(buff));
        close(fd);

        if(nr == -1)
        {
                /*error*/
        }

        /*read()函数*/
         fd = open("/data/joyyzhang/mypro/test.cpp",
                     O_RDONLY);

        if(fd == -1)
        {
                /*error*/
        }

        int len=100;
        char buf[len];

        while(len != 0 && (nr = read(fd,buf,len)) != 0)
        {
                if(nr == -1)
                {
                        /*error*/
                }
                printf("%s",buf);
                memset(buf,0,sizeof(buf));
        }
        close(fd);

}