How can I obtain a file's size in C?

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How do you determine the size of a file in C?

How can I obtain a file's size in C? I opened with an application written in C. I would like to know the size, because I want to put the content of the loaded file into a string, which I alloc using malloc(). Just writing malloc(10000*sizeof(char)

the stat(2) system call, which a quick google should've told you — tbert, Apr 17 '12 at 07:02
What platform are you targeting? Or do you intend for this to be cross-platform? — Cody Gray - on strike, Apr 17 '12 at 07:05
Also, it's already been answered here: http://stackoverflow.com/questions/238603/how-can-i-get-a-files-size-in-c — Rich Drummond, Apr 17 '12 at 07:06
Is it necessary to hold the whole file in memory at the same time? — DavidO, Apr 17 '12 at 07:16
wow,it's already been answered in fact! It's my fault,thanks for reminding me. — EricDai, Apr 17 '12 at 07:17

score 3 · Accepted Answer · answered Apr 17 '12 at 07:06

3

You can use the fseek and ftell functions:

FILE* f = fopen("try.txt","rb");
fseek(f, 0, SEEK_END);
printf("size of the file is %ld", ftell(f));

answered Apr 17 '12 at 07:06

Ivaylo Strandjev

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+1 for the easy way i also always using. fstat / stat would be the other way. – Jonas Schnelli Apr 17 '12 at 07:07

score 1 · Answer 2 · answered Apr 17 '12 at 07:07

1

for file size, stat, lstat or fstat will be the right choice.

pleas check stat

answered Apr 17 '12 at 07:07

agfe2

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score 0 · Answer 3 · answered Apr 17 '12 at 07:08

    int Get_Size( string path )
{

FILE *pFile = NULL;

// get the file stream

fopen_s( &pFile, path.c_str(), "rb" );


// set the file pointer to end of file

fseek( pFile, 0, SEEK_END );

// get the file size

int Size = ftell( pFile );

// return the file pointer to begin of file if you want to read it

rewind( pFile );

// close stream and release buffer

fclose( pFile );

return Size;
}

more answers cplusplus.com

score 0 · Answer 4 · answered Apr 17 '12 at 07:08

0

You can position yourself at the end of the file with fseek and use ftell() for that:

FILE *fd;
fd = fopen("filename.txt","rb");
fseek ( fd, 0 , SEEK_END );
int fileSize = ftell(fd);

filesize will contain the size in Bytes.

gekod

answered Apr 17 '12 at 07:08

Helder AC

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score 0 · Answer 5 · answered Apr 17 '12 at 07:11

I thought there was a standard C function for this, but I couldn't find it.

If your file size is limited, you can use the solution proposed by izomorphius.

If your file can be larger than 2GB then you can use the _filelengthi64 function (see http://msdn.microsoft.com/en-us/library/dfbc2kec(v=vs.80).aspx). Unfortunately, this is a Microsoft/Windows function so it's probably not available for other platforms (although you will probably find similar functions on other platforms).

EDIT: Look at afge2's answer for the standard C function. Unfortunately, I think this is still limited to 2GB.

How can I obtain a file's size in C?

5 Answers5