How to get size of file in visual c++?

Question

Below is my code. My problem is, my destination file always has a lot more strings than the originating file. Then, inside the for loop, instead of using i < sizeof more, I realized that I should use i < sizeof file2 . Now my problem is, how to get the size of file2?

int i = 0;

FILE *file2 = fopen(LOG_FILE_NAME,"r");
wfstream file3 (myfile, ios_base::out);


// char more[1024];
char more[SIZE-OF-file2];


for(i = 0; i < SIZE-OF-file2 ; i++)
{       
    fgets(more, SIZE-OF-file2, file2);
    file3 << more;
}

fclose(file2);
file3.close();

Answer 1

You can do this using GetFileSize(). By reading the size of the file from the filesystem, you will avoid a lot of unnecessary computation. This can also be done with _stat(), or on unix it would just be stat().

Here is the definition:

DWORD WINAPI GetFileSize( __in HANDLE hFile, __out_opt LPDWORD lpFileSizeHigh );

Doc for GetFileSize:

http://msdn.microsoft.com/en-us/library/aa364955%28VS.85%29.aspx

Alternatively you might want to use _stat()

Doc for stat: http://msdn.microsoft.com/en-us/library/14h5k7ff%28VS.80%29.aspx

Answer 2

The most basic way is to fseek to the end of the file and to use ftell to give you the offset. The other (stat) functions also do this, but they're not cross-platform. Of course, if you want your code rot in hell, you could also use GetFileSize().

fseek(file, 0, SEEK_END);
off_t offset = ftell(file);
fseek(file, 0, SEEK_SET);

Every time you refer to C as Visual C, or C++ as Visual C++ I die a little.