Creating a folder if it doesn't exists in C, with fopen? How?

[crazyfuturamanoob]

So how to do this? fopen doesn't do it automatically, it just returns NULL if folder doesn't exists.

I'm stuck. Nothing with google. And any of my C books don't help it.

[WW]

You can use the stat library function get information about a file or directory, and the mkdir library function to create a directory. Here's an example you can experiment with:

stat_test.c


#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <stdio.h>

extern int errno;

int main()
{
int e;
struct stat sb;
char *name = "tmp999";

e = stat(name, &sb);
printf("e=%d errno=%d\n",e,errno);
if (e == 0)
{
if (sb.st_mode & S_IFDIR)
printf("%s is a directory.\n",name);
if (sb.st_mode & S_IFREG)
printf("%s is a regular file.\n",name);
// etc.
}
else
{
printf("stat failed.\n");
if (errno = ENOENT)
{
printf("The directory does not exist. Creating new directory...\n");
// Add more flags to the mode if necessary.
e = mkdir(name, S_IRWXU);
if (e != 0)
{
printf("mkdir failed; errno=%d\n",errno);
}
else
{
printf("created the directory %s\n",name);
}
}
}
return 0;
}


Compile and run:


$ gcc stat_test.c
$ ./stat_test
e=-1 errno=2
stat failed.
The directory does not exist. Creating new directory...
created the directory tmp999
$ ./stat_test
e=0 errno=0
tmp999 is a directory.
$

[wmcbrine]

BTW, one reason this might not show up in a general C book is that, unlike fopen(), it's not part of ANSI standard C -- mkdir() is POSIX-specific. Just something to be aware of if portability is an issue. (There is no ANSI way to create directories.)