C++中如何获取文件大小的总结

转载自 http://www.soft568.com/info/detail/4-5662.html

（一）

 

对文件操作时有时获得文件的大小时必要的.下面是获得其大小小的较简单方法.
#include<io.h>   //C语言头文件
#include<iostream>   //for system();
using namespace std;
int main()
{
  int handle;
  handle = open("test.txt", 0x0100); //open file for read
  long length = filelength(handle); //get length of file
  cout<<"file length in bytes:"<<length<<endl;
  close(handle);
 
  system("pause");
  return 0;
}

 

（二）

 

//用Windows API 中的 GetFileSize()获得文件长度
//假设文件file.txt 在当前目录下
//file.txt的内容为:123abc
//关于windows API函数情参考部分windows API函数或MSDN
#include <iostream>
#include <windows.h>   //for windows api
using namespace std;
int main()
{
  //用API函数CreateFile()创建文件句柄
  HANDLE fhadle = CreateFile("file.txt",           //文件名或路径
                                  0,
                                  0,
                                  0,
                                  OPEN_EXISTING, //文件存在则打开并读取
                                  0,
                                  0);
  DWORD size = GetFileSize(fhadle,0);
  cout<<"size:"<<size<<endl;
  return 0;
}
//输出:
size:6

（三）

//假设文件file.txt存在,且在当前目录下

#include <iostream>
#include <fstream>

using namespace std;
int main(int argc, char* argv[])
{
    ifstream in("file.txt");
    in.seekg(0, ios::end);      //设置文件指针到文件流的尾部
    streampos ps = in.tellg();  //读取文件指针的位置
    cout << "File size: " << ps << endl;
    in.close();                 //关闭文件流
    return 0;
}

 

 

以上部分转自http://blog.sina.com.cn/u/1066677252

（四）

 

在VC中，CFILE的GetLength()函数可直接得到大小：

CFile cf;

 // Attempt to open thefile for reading.
 if( !cf.Open( pszFilename, CFile::modeRead ) )
  return( FALSE );

 // Get the size of the file and store
 // in a local variable. .
 DWORD dwSize;
 dwDibSize = cf.GetLength();

 

(五)
#include <sys/types.h>;
#include <sys/stat.h>;

long
get_filesize(char *filename)
{
    struct stat     f_stat;
    if (stat(filename, &f_stat) == -1) {
        return -1;
    }
    return (long)f_stat.st_size;
}

(六)

int main(void)
{
   struct stat statbuf;
   FILE *stream;

   /* open a file for update */
   if ((stream = fopen(FILENAME, "w+")) == NULL)
   {
      fprintf(stderr, "Cannot open output file.\n");
      return(1);
   }

   /* get information about the file */
   stat(FILENAME, &statbuf);

   fclose(stream);

   /* display the information returned */
   if (statbuf.st_mode & S_IFCHR)

      printf("Handle refers to a device.\n");
   if (statbuf.st_mode & S_IFREG)
      printf("Handle refers to an ordinary file.\n");
   if (statbuf.st_mode & S_IREAD)
      printf("User has read permission on file.\n");
   if (statbuf.st_mode & S_IWRITE)
      printf("User has write permission on file.\n");

   printf("Drive letter of file: %c\n", 'A'+statbuf.st_dev);
   printf("Size of file in bytes: %ld\n", statbuf.st_size);
   printf("Time file last opened: %s\n", ctime(&statbuf.st_ctime));

   return 0;
}

(七)

#include <sys\stat.h>;
#include <string.h>;
#include <stdio.h>;
#include <fcntl.h>;
#include <io.h>;

int main(void)
{
    int handle;
    char msg[] = "This is a test";
    char ch;

    /* create a file */
    handle = open("TEST.$$$", O_CREAT | O_RDWR, S_IREAD | S_IWRITE);

    /* write some data to the file */
    write(handle, msg, strlen(msg));

    /* seek to the beginning of the file */
    lseek(handle, 0L, SEEK_SET);

    /* reads chars from the file until we hit EOF */

    do
    {
       read(handle, &ch, 1);
       printf("%c", ch);
    }  while (!eof(handle));

    close(handle);
    return 0;
}

 

八 这种方法刚在Dev-cpp上实验过

#include <iostream>
#include <fstream>

using namespace std;

int main(int argc, char * argv[])
{
    if (argc>1)
    {
      cout<<argv[1]<<endl;
      ifstream in(argv[1]);
      if (!in) return (-1);
     
      in.seekg(0, ios_base::end);
      streampos pos=in.tellg();
      
      cout<<"file size "<<pos<<endl;
    }
    else     return -1;
    return 0;
}