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Solved
C function to determine if a directory exists
Posted on 2011-03-04
Using C (not C++):
I have often used the C function access() to determine if a file exists e.g
if (!access(filename, F_OK))
printf("File exists);
else
printf("File does NOT exist\n");
For my current purposes, I need to be able to tell if a particular SUBDIRECTORY exists.
e..g if I have a subdir "STEVE", and pass "STEVE" to access() it will return 0, but I need to be able to tell if "STEVE" is a subdir, rather than a file. Is there a function that can help me out?
Thanks,
Steve
I have often used the C function access() to determine if a file exists e.g
if (!access(filename, F_OK))
printf("File exists);
else
printf("File does NOT exist\n");
For my current purposes, I need to be able to tell if a particular SUBDIRECTORY exists.
e..g if I have a subdir "STEVE", and pass "STEVE" to access() it will return 0, but I need to be able to tell if "STEVE" is a subdir, rather than a file. Is there a function that can help me out?
Thanks,
Steve
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17 Comments
Active 1 day ago
Hi Steve,
One of the stat() functions should do nicely.
GoodLuck,
Kent
One of the stat() functions should do nicely.
GoodLuck,
Kent
#include <sys\stat.h>
#include <stdio.h>
#include <time.h>
int main(void)
{
struct stat statbuf;
int handle;
// int stat(const char *path, struct stat *statbuf);
stat ("c:\\mypath\\dirname", &statbuf);
if (statbuf.st_mode & S_S_IFDIR)
printf("Directory....\n");
}
Active today
you can use readdir and get the file stats:
http://www.ibm.com/developerworks/aix/library/au-unix-readdir.html
"The stat() function fills a struct stat structure with information about a specific file; if you've got a file descriptor instead of a file name, you can use the fstat() function instead."
•"S_ISDIR(mode) -- Is this a directory?"
•"S_ISREG(mode) -- Is this a regular file?"
http://www.ibm.com/developerworks/aix/library/au-unix-readdir.html
"The stat() function fills a struct stat structure with information about a specific file; if you've got a file descriptor instead of a file name, you can use the fstat() function instead."
•"S_ISDIR(mode) -- Is this a directory?"
•"S_ISREG(mode) -- Is this a regular file?"
Kent,
Welk. I tried your code, but it seems that the identifier
S_S_IFDIR
is not included in my
sys\stat.h
nor
sys\types.h
even though stat() is prototyped in stat.h.
Any idea what I'm doing wrong?
Thanks!
Welk. I tried your code, but it seems that the identifier
S_S_IFDIR
is not included in my
sys\stat.h
nor
sys\types.h
even though stat() is prototyped in stat.h.
Any idea what I'm doing wrong?
Thanks!
Active today
Or, just a typo: try S_IFDIR instead.
http://linux.die.net/man/2/stat
http://linux.die.net/man/2/stat
>>
S_ISDIR(mode) -- Is this a directory
Not sure I understand this. What is mode?
I see in sys\stat.h that
#define S_ISDIR( m ) (((m) & S_IFMT) == S_IFDIR)
is a macro, but not sure what to pass to it.
Thanks
S_ISDIR(mode) -- Is this a directory
Not sure I understand this. What is mode?
I see in sys\stat.h that
#define S_ISDIR( m ) (((m) & S_IFMT) == S_IFDIR)
is a macro, but not sure what to pass to it.
Thanks
Look like both S_IFDIR and S_ISDIR exist in stat.h
#define S_IFDIR 0040000 /* directory */
#define S_ISDIR( m ) (((m) & S_IFMT) == S_IFDIR)
Still..need to know..what do I pass in as the parameter "mode"?
Thanks.
#define S_IFDIR 0040000 /* directory */
#define S_ISDIR( m ) (((m) & S_IFMT) == S_IFDIR)
Still..need to know..what do I pass in as the parameter "mode"?
Thanks.
Phoffric:
I see the two links you posted are from UNIX and Linux. Do they apply to WIndows/DOS 16-bit programming?
Thanks
I see the two links you posted are from UNIX and Linux. Do they apply to WIndows/DOS 16-bit programming?
Thanks
Active 1 day ago
Hi Steve,
Sorry about the typo.
S_IFDIR is a constant. This constant is a bit that flags the item as a directory.
S_ISDIR(m) is a macro. You would pass statbut->st_mode to it.
I corrected the item and reposted the source code.
Give it a try,
Kent
Sorry about the typo.
S_IFDIR is a constant. This constant is a bit that flags the item as a directory.
S_ISDIR(m) is a macro. You would pass statbut->st_mode to it.
I corrected the item and reposted the source code.
Give it a try,
Kent
#include <sys\stat.h>
#include <stdio.h>
#include <time.h>
int main(void)
{
struct stat statbuf;
int handle;
// int stat(const char *path, struct stat *statbuf);
stat ("c:\\mypath\\dirname", &statbuf);
if (statbuf.st_mode & S_IFDIR)
printf("Directory....\n");
}
OK, I think I got it.
Just to be safe, I first use access() to determine if the file exists: Then I invoke stat...
Please do not assume this code is perfect. I did only cursory testing.
Thanks everyone!
isdir-c.txt
Just to be safe, I first use access() to determine if the file exists: Then I invoke stat...
Please do not assume this code is perfect. I did only cursory testing.
Thanks everyone!
isdir-c.txt
Actually I defer to Kent. You don't need to include <sys\types.h>. Points to be awaeded shortly. Thanks!
Kent,
Thank you. Your solution had everything in one place so you get the points
phoffric: - As per the above, Kent got the points, but I still appreciate your help. If you feel that you should share in the points, feel free t respond; however, I won't be able to handle your request 'til at least next Thursday as I am going to be on a short vacation. Thanks for your efforts.
Thank you. Your solution had everything in one place so you get the points
phoffric: - As per the above, Kent got the points, but I still appreciate your help. If you feel that you should share in the points, feel free t respond; however, I won't be able to handle your request 'til at least next Thursday as I am going to be on a short vacation. Thanks for your efforts.
Active today
>> Do they apply to WIndows/DOS 16-bit programming
I didn't realize you were working in Windows/DOS 16-bit programming. And I don't have that product available to test, so I cannot be sure.
But, I tried the kdo's post in VS 2010 Express, and it works fine (with the typo corrected), so that is a good sign that it will work for you.
Since S_ISDIR is defined for you (it is not defined in sys\stat.h in VS 2010 Express), I think the below code should work for you since it works in Linux. However, you need to verify using your DOS-16 system.
I didn't realize you were working in Windows/DOS 16-bit programming. And I don't have that product available to test, so I cannot be sure.
But, I tried the kdo's post in VS 2010 Express, and it works fine (with the typo corrected), so that is a good sign that it will work for you.
Since S_ISDIR is defined for you (it is not defined in sys\stat.h in VS 2010 Express), I think the below code should work for you since it works in Linux. However, you need to verify using your DOS-16 system.
if (statbuf.st_mode & S_IFDIR)
printf("Directory....\n");
if( S_ISDIR( statbuf.st_mode ) )
printf("S_ISDIR works in Linux\n");
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