在C中写入文件时,额外字符添加到缓冲区

Question

m为了尝试在C中制作文件的备份副本,我发现下面的算法有时会产生额外的字符.我也尝试在while循环中声明readBuffer ,但这并没有解决问题.这是问题的一个例子.

原始文件内容

Hello there. 
My name is Alice. 
Done.

备份文件内容

Hello there. 
My name is Alice.
Done.ice

如您所见,在之前缓冲的消息的最后一行中留下了字符.这只发生在文件的最后几行,因为任何其他时间缓冲区都填充了新内容.如何纠正我的逻辑以解决此问题？

while(0 != bytesRead)
{      
    bytesRead = read(fdRead,readBuffer, BUFFER_SIZE);      
    if(0>bytesRead)
    {
      fprintf(stderr,"read() on '%s' for backup failed.\nError Info: %s\n",fileName,strerror(errno));
      exit(EXIT_FAILURE);
    }
    else if(0<bytesRead)
    {
      if(-1 == write(fdWrite,readBuffer,BUFFER_SIZE))
        {
          fprintf(stderr,"An error occurred while writing backup for '%s'.\nError Info: %s\n",fileName,strerror(errno));
          exit(EXIT_FAILURE);
        }
    }
}

Answer 1

尝试:write(fdWrite,readBuffer,bytesRead).