eg.cpp

linux下文件的读写操作 linux下文件的读写操作

/*
 *      eg.cpp
 *      
 *      Copyright 2009 Lee <lee@lee-laptop>
 *      
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *      
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *      
 *      You should have received a copy of the GNU General Public License
 *      along with this program; if not, write to the Free Software
 *      Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *      MA 02110-1301, USA.
 */

#include <iostream>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
using namespace std;

#define buffer_size 1024

int main(int argc,char **argv)
{
 
 int from_fd,to_fd;
 int bytes_read,bytes_write;
 char buffer[buffer_size];
 char *ptr;

int strcont1=0;
	int strcont2=0;
    
    char path1[50]={NULL};
    cout<<"请输入源文件路径:"<<endl;
    cin>>path1;
    
    char path2[50]={NULL};
    cout<<"请输入目标文件路径:"<<endl;
    cin>>path2;
    
    for(int i=0;i<50;i++)
    {
    	if(path1[i]!=NULL)
    	strcont1++;
    	else 
    	   break;
    }
    
    for(int i=0;i<50;i++)
    {
    	if(path2[i]!=NULL)
    	strcont2++;
    	else 
    	   break;
    }
    //cout<<path1<<strcont<<endl;
    char* oldpath=new char[strcont1];
    char* newpath=new char[strcont2];
    
    for(int j=0;j<strcont1;j++)
    {
    	oldpath[j]=path1[j];
    }
    
    for(int j=0;j<strcont2;j++)
    {
    	newpath[j]=path2[j];
    }
    //cout<<oldpath<<" and "<<newpath;

/* if(argc!=3)
  {
fprintf(stderr,"usage:%s fromfile tofile\n\a",argv[0]);
exit(1);
  }
    */

 if((from_fd=open(oldpath,O_RDONLY))==-1)
  {
fprintf(stderr,"open %s error:%s\n",argv[1],strerror(errno));
exit(1);
 }


 if((to_fd=open(newpath,O_WRONLY|O_CREAT,S_IRUSR|S_IWUSR))==-1)
  {
        fprintf(stderr,"open %s error:%s\n",argv[2],strerror(errno));
        exit(1);
 }
 

 while(bytes_read=read(from_fd,buffer,buffer_size))
 {
   if((bytes_read==-1)) break;
   else if(bytes_read>0)
       {
  ptr=buffer;
  while(bytes_write=write(to_fd,ptr,bytes_read))
   {
     if((bytes_write==-1))break;
     else if(bytes_write==bytes_read) break;
     else if(bytes_write>0)
           {
      ptr+=bytes_write;
   bytes_read-=bytes_write;
          }
          }
         if(bytes_write==-1)break;

       }
  }
 close(from_fd);
 close(to_fd);
 exit(0);
}