Folder access library

This is a discussion on Folder access library within the C++ Programming forums, part of the General Programming Boards category; I have a file with about 200-300 images and I want to perform some functions on them all but I ...

  1. #1
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    Folder access library

    I have a file with about 200-300 images and I want to perform some functions on them all but I don’t want to have to go to the trouble of having to type out
    CvLoadImage(“img1.jpg”); run program than edit it to CvLoadImage(“img2.jpg”); run program ect.
    There are no order to the names of the files there called random things.

    Basically I want my program to access the folder they will be in, select each image one at a time, and run it once for the lot of them.
    What function or libry should I look at to help with this?

    Is there one that can count the amount of files in a folder and select there names and pop it into a variable so I can do something along the lines like this
    Code:
    Loop till end of folder{
    a=name of file.jpg;
    CvLoadImage(a);
    }
    Last edited by aprop; 11-07-2010 at 02:34 PM.

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    Use the right tool for the right job; use a shell script in this case.
    iMalc: Your compiler doesn't accept misspellings and bad syntax, so why should we?
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    In C++, the approach to do this is specific to the operating system.

    If doing this under windows, look up the functions FindFirstFile() and FindNextFile() in the win32 API.

    Under most (I'd hesitate to say all) flavours of unix, look up the functions findfirst() and findnext().

    You might also try the boost filesystem library (look up the directory_iterator class). There are trade-offs with using that library, but it does aim for portability - and is/was the basis for a proposal to include such functionality in a future C++ standard (I'm not sure of the status of that, offhand - I seem to recall some concerns with an "illusion of portability" in discussion).
    Right 98% of the time, and don't care about the other 3%.

  4. #4
    Registered User ssharish2005's Avatar
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    Have a read the FAQ for files and directory handling.

    ssharish
    Life is like riding a bicycle. To keep your balance you must keep moving - Einstein

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    and the hat of wrongness Salem's Avatar
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    Or from the command line

    myprog.exe *.jpg

    Then munch your way through the argv[] of your main, processing each file.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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    Quote Originally Posted by Salem View Post
    Or from the command line

    myprog.exe *.jpg

    Then munch your way through the argv[] of your main, processing each file.
    That only works with a command shell that expands wild cards.

    It does not, for example, work with the windows command line - myprog.exe will receive "*.jpg" as argv[1].
    Right 98% of the time, and don't care about the other 3%.

  7. #7
    and the hat of wrongness Salem's Avatar
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    Well if you link it with setargv, it will.
    Expanding Wildcard Arguments

    TBH, that took a while to find. I'd forgotten just how badly M$ command line sucks even after 30+ years.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

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    Quote Originally Posted by Salem View Post
    I'd forgotten just how badly M$ command line sucks even after 30+ years.
    It is easy to forgive one who manages to forget the incomprehensible

    Although, if you respect its limits, the MS command line program is not bad. Of course, those limits test your ability to show respect.
    Right 98% of the time, and don't care about the other 3%.

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    Hey thanks for the feedback.
    Im working in windows 7 using visual studio 2010.
    Quote Originally Posted by MWAAAHAAA View Post
    Use the right tool for the right job; use a shell script in this case.
    Quote Originally Posted by ssharish2005 View Post
    Have a read the FAQ for files and directory handling.

    ssharish
    Im using windows from what I read about Shell scripts and from what I read in the faq Im not sure if they apply, unistd wouldn’t work in my #include for example.
    I could be wrong though if I am let me know .

    Quote Originally Posted by grumpy View Post
    In C++, the approach to do this is specific to the operating system.

    If doing this under windows, look up the functions FindFirstFile() and FindNextFile() in the win32 API.

    Under most (I'd hesitate to say all) flavours of unix, look up the functions findfirst() and findnext().

    You might also try the boost filesystem library (look up the directory_iterator class). There are trade-offs with using that library, but it does aim for portability - and is/was the basis for a proposal to include such functionality in a future C++ standard (I'm not sure of the status of that, offhand - I seem to recall some concerns with an "illusion of portability" in discussion).
    This is where most of my attention has been the last 2 days trying to use these functions with opencv.
    Now I can pull all the files in my folder but they are not feeding into my cvLoadImage function.
    Can anyone see what I may be doing wrong?
    Code:
    void findf()
    {
    	
    	//directory varibles
    	LPCTSTR lpFileName;
    	HANDLE hfind1;
    	TCHAR hj;
    	//opencv image
    	IplImage* Image;
    	//string and char array
    	string name;
    	char name1[100];
    	//counters
    	int i=0;
    	int q=0;
    	 //not my real directory but my path name is correct, and pulling the bmp files
    	 lpFileName=TEXT("c:/mydir"); 	 
    	
    WIN32_FIND_DATA FileData;
    hfind1=FindFirstFile(lpFileName,&FileData);
    
    do{		
    		q++;
    		//print out file name
    		_tprintf(FileData.cFileName);
    		cout<<" "<<q<<"\n ";
    //this puts the cFileName into a char array name1
    do {
                                    name1[i]=(1,FileData.cFileName[i]);
                                    //up i
                                    i++;
    
    }
    
    while(FileData.cFileName[i]!=0);
    
    //once we have out name1, bring i to 0 once more
    cout<<name1<<" \n";
    
    //here images are inputted ,but not been displayed
    Image=cvLoadImage(name1);
    cvShowImage("new",Image);
    
    
    // release the image
    cvReleaseImage(&Image);
    
    //return i to 0 and clear the name1 array
    for(i;i!=-1;i--)
    {
    //clear name1 array
    name1[i]=0;
    
    }
    
    
    }
    //find the next file
    while(FindNextFile(hfind1,&FileData)!=0);
    
    //close the hfind
    FindClose(hfind1);
    
    }
    Also on another note I noticed 2 files called
    . and ..
    are these just back tracks to the folder before hand, i managed to discard them using the wild card operator *?
    Last edited by aprop; 11-10-2010 at 09:21 AM. Reason: typo

  10. #10
    and the hat of wrongness Salem's Avatar
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    Yes, . is the current directory, and .. is the parent directory.

    And is that the best job you could manage on the indentation front?
    SourceForge.net: Indentation - cpwiki
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

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