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How do i find out if a file is locked?

73 New Member
How can I determine if the file is locked. I have looked everywhere and I get mixed answers and I can't get this going.

I know this is easy for some, but please post a quick sol.

Jan 13 '09 #1
34 22349
2,426 Recognized Expert Top Contributor
Who [what application] is locking the file in question and how is it being accomplished?

A file might be locked via a system call -- you need to tell us what operating system you're using.

Some applications perform their own ad-hoc file locking and unlocking -- you need to tell us what application.

In either case, it should be clear that file locking is idiosyncratic. There is no single portable way to determine if a file is locked.
Jan 13 '09 #2
1,275 Recognized Expert Top Contributor
This is one of a common question and the answer is no.
There is no system call to do this

Jan 14 '09 #3
73 New Member
I am running Windows XP.

The file is being locked by a 3rd party software. As far as I am concerned the application is doing the locking and unlocking.

This is what happens:
I create a project using this application. The project has x number of files. When the project is open, one file (JUST ONE) gets locked.

gpraghuram - you mentioned that there is no way to determine if a file is locked. I use winzip to zip/backup the project files at least once a day. Winzip notices that this file cannot be zipped due to the fact that it is being used.

This is the error I get from winzip after trying to zip the project files while the project is up and running.

Warning: The following file is open by another program. If that program
Warning: writes to the file while WinZip is zipping the file, the zipped
Warning: file may be corrupt: C:\Rhapsody\Mod el\JDW341\myscr ipts.vba

My question is, how does Winzip know? That is the same function/api call that I am looking for in my program that I am writing.

Do you guys have any ideas?
Jan 14 '09 #4
9,065 Recognized Expert Moderator Expert
WinZip noticed because it tried to open the file and was unable to, you could try the same thing but the important point is that it is non-portable and just being able to open a file doesn't mean another program isn't using it.
Jan 14 '09 #5
73 New Member
I see what you mean.
In my case it should be ok since that file will only open by that specific program.

Jan 14 '09 #6
73 New Member
I dont think opening the file is cutting it. I open the file with no errors. I believe it might be when you try to save it.

I can't imaging Winzip trying to save every file to see if it can copy it or not. :\
Jan 14 '09 #7
9,065 Recognized Expert Moderator Expert
try opening it for write access
Jan 14 '09 #8
73 New Member
this is what i have:

#include <iostream>
#include <fstream>
using namespace std;

int main ()
ofstream myfile ("C:\\Rhapsody\ \Model\\JDW341\ \LR240.vba");

if (myfile.is_open ())
cout << "access granted.\n";
system("PAUSE") ;

else { cout << "access denied.\n"; system("PAUSE") ; }
return 0;
Jan 14 '09 #9
9,208 Recognized Expert Moderator Expert
You might try using actual Win32 calls to get your file access instead of just using ANS C++. As far as ANS C++ goes, if the file exists, it will open.

System Software Win32 File API
Jan 14 '09 #10

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