Get size of file using C

[zootreeves]

Is there an easy way to get the size of a file, using C. Here is what i have got so far:

int filesize;
struct stat file_status;
stat("./tmp.xml", &file_status);
printf("%d", file_status.st_size);
printf("<B>Written file</B> ./tmp.xml - <B>File Size:</B> %d<BR>", filesize);

But this always returns 0 bytes because st_size is not an int.

‘crawler.c:120: warning: format ‘%llu’ expects type ‘long long unsigned int’, but argument 2 has type ‘__off_t’


How can I print type '__off_t'

[thumper]

Not an answer I'm afraid, but this sort of issue is one of the reasons I love C++ :)

[thumper]

Are you sure you're showing us the correct line?

The compiler shouldn't be changing your %d to a %llu

Just a guess, but perhaps the offset is just an unsigned long int, not an unsigned long long int. Try %lu.

[rydow]

This works
File main.c looks like:
/************************************/
#include <stdio.h>
#include <sys/stat.h>
int main(){
struct stat file_status;
if(stat("main.c", &file_status) != 0){
perror("could not stat");
}
printf("%d\n", file_status.st_size);
}
/************************************/
Are you sure that you actually get the file_status filled, you don't check the return of stat?

/J

[zootreeves]

found the solution:


stat("./tmp.xml", &file_status);
printf("<BR><B>Written file</B> ./tmp.xml - <B>File Size:</B>%9jd Kb<BR><BR>", ((intmax_t)file_status.st_size) / 1024);

I've got a new question now. Is is possible to run a shell command within a C program? I want to run curl (without using libcurl).

[fct]

man 3 exec (if you have manpages-dev installed)

[zootreeves]

Thanks that was just what i was looking for. One more question tho, i promise it will be the last one :)

How can i stop libcurl printing the result to screen, I would like it in a string instead.



CURL *curl;

curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "http://url.com");
curl_easy_setopt(curl, CURLOPT_POST, 1);
curl_easy_setopt(curl, CURLOPT_TRANSFERTEXT, 0);
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, data_forcurl);
curl_easy_setopt(curl, CURLOPT_HEADER, 0);
curl_easy_perform(curl);

/* always cleanup */
curl_easy_cleanup(curl);
}

[Codecaine_21]

.

[worksofcraft]

The following code

opens a file
determines it's size
allocates memory for it
reads the file to memory
closes the file




char *AllData = NULL;
int FD = open(FileName, O_RDONLY);
if (FD < 0) {
fprintf(stderr, "file %s open failed\n", FileName);
return;
}
struct stat StatBuf;
fstat(FD, &StatBuf);
AllData = (char *) malloc(StatBuf.st_size+1); // + null terminator

if (!read(FD, AllData, StatBuf.st_size)) {
fprintf(stderr, "file read error\n");
}
AllData[StatBuf.st_size] = '\0';
close(FD);


p.s. with 20/20 hind-sight I see you should really check that malloc succeeded ;)

[bouncingwilf]

Try this bit of code, I googled this one as it was quicker than finding my own implementation!

/*
** FLENGTH.C - a simple function using all ANSI-standard functions
** to determine the size of a file.
**
** Public domain by Bob Jarvis.
*/

#include <stdio.h>
#include <io.h>

long flength(char *fname)
{
FILE *fptr;
long length = 0L;

fptr = fopen(fname, "rb");
if(fptr != NULL)
{
fseek(fptr, 0L, SEEK_END);
length = ftell(fptr);
fclose(fptr);
}

return length;
}

#ifdef TEST

void main(int argc, char *argv[])
{
printf("Length of %s = %ld\n", argv[0], flength(argv[0]));
}

#endif /* TEST */