file size in c program

Question

I just want to find the file size with the help of c program..I wrote a code but it give wrong result...

fseek(fp,0,SEEK_END);
osize=ftell(fp);

Is there any other way?

What do you mean "wrong result"? What did you get, what were you expecting, and why did you expect it? Also, how did you open the file? — David Thornley, Apr 22 '11 at 16:07
@Sujoy::Can you right-click your file and see the size in properties? What is the size there? — Sadique, Apr 22 '11 at 16:17
Okay, now tell us how `osize` is declared, what the negative value was, and about how big the file really is. There is a possibility that the value is too big for `osize`, but without information it's hard to tell. — David Thornley, Apr 22 '11 at 17:09

score 2 · Answer 1 · answered Apr 22 '11 at 16:06

2

The stat system call is the usual solution to this problem. Or, in your particular case, fstat.

answered Apr 22 '11 at 16:06

bmargulies

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score 2 · Answer 2 · answered Apr 22 '11 at 16:25

ftell returns an int. If you are on a system where int is 32 bits and your file is more than 2GB, you may very well end up with a negative size. POSIX provides ftello and fseeko which use a off_t. C has fgetpos and fsetpos which use a fpos_t -- but fpos_t is not an arithmetic type -- it keeps things related to the handling of charset by the locale for instance.

Sadique · Answer 3 · 2011-04-22T16:25:21.427

1

There is no reason why it should not work.

Is there any other way? You can use stat, if you know the filename:

struct stat st;
stat(filename, &st);
size = st.st_size;

By the way ftell returns a long int

The sys/stat.h header defines the structure of the data returned by the functions fstat(), lstat(), and stat().

edited Apr 22 '11 at 16:25

answered Apr 22 '11 at 16:08

Sadique

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where is the definition of stat or what the body of stat contain? – Sujoy Apr 22 '11 at 16:21
@Sujoy:: See the edit. Btw you did not tell the size of your file by simply right-clicking on it and checking properties. – Sadique Apr 22 '11 at 16:25

score 0 · Answer 4 · answered Apr 22 '11 at 16:07

0

Try using _filelength. It's not portable, though... I don't think there's any completely portable way to do this.

answered Apr 22 '11 at 16:07

user541686

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_filelength doesn't work with file pointers. However you can always do this: size = _filelength(_fileno(fp)); – Tim Ring Sep 20 '12 at 10:31

score 0 · Answer 5 · answered Apr 22 '11 at 16:18

Try this using fstat():

int file=0;
if((file=open(<filename>,O_RDONLY)) < -1)
    return -1; // some error with open()

struct stat fileStat;
if(fstat(file,&fileStat) < 0)    
    return -1; // some error with fstat()

printf("File Size: %d bytes\n",fileStat.st_size);

score 0 · Answer 6 · answered Apr 23 '11 at 14:08

The only negative return value by ftell is -1L if an error occurs. If you don't mind using WinAPI, get file size with GetFileSizeEx:

HANDLE hFile = CreateFile(filename, 
                          GENERIC_READ,
                          0, 
                          NULL,
                          OPEN_EXISTING, 
                          FILE_ATTRIBUTE_NORMAL, 
                          NULL);

LARGE_INTEGER size;
GetFileSizeEx(hFile, &size);
printf("%ld", size.QuadPart);

CloseHandle(hFile);

file size in c program

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