C/C++如何获得文件大小

（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;

}
http://blog.chinaunix.net/uid-20419589-id-1683546.html