Linux读取文件及获得文件大小方法

以下代码演示如果取得文件"/data/temp.jpg”大小及读取文件前256Bytes

 

#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/stat.h>

int main()
{
  int fbfd = 0;
  int size,nread,n;
  char c,buffer[256];
  struct stat buf;

  if (stat("/data/temp.jpg",&buf)<0)
  {
    printf("can't get file infomation.");
    return (0);
  }

  size = buf.st_size;
  fbfd = open("/data/temp.jpg", O_RDONLY);
  if (!fbfd)
  {
      printf("Error: cannot open file.\n");
      return(1);
  }

/* // 这也是一种取得文件大小的方法,不过很条
  size = 0;
  while ( (nread = read(fbfd,buffer,sizeof(buffer))) > 0)
  {
    size += nread;
  }
*/
  printf("Size=%d\n",size);

  lseek(fbfd,0,SEEK_SET);
  //while(1)
  {
    nread = read(fbfd,buffer,256);
    if(nread > 0)
    {
      for(n=0;n<nread;n++)
      {
        printf("%c",buffer[n]);
      }
      printf("\n");
    }
    else
    {
      printf("Read error, nread=%d\n",nread);
      //break;
    }
  }
  printf("Read end\n");
  return (0);

}
 
在Android2.1 Emulator上输出如下: