Looking for right fopen mode for my problem - fopen

I have created this programming problem where I read list of books from a binary file into array of structs. If the file does not exist, then I want the program to create the file.
In this case, I ask the user to enter the books and their authors. Then I write this to the file as series of structs.
If the file already exists with some books (with authors) on it, I want to give an option to the user to either keep, delete or update the book entry of the file.
And if the user deletes some books, then user should be given option to enter number of books as long as some limit (MAX BOOKS) is not reached.
I am confused as to which mode should I use to open the file using fopen.
If r+b mode is used, then there will be an error if the file doesn't exist.
If a+b mode is used then writing can only be appended. So, if the user has decided to delete some books, and enter other books, this information will be be sequentially appended to the file.
How can this problem be approached ?

I found a solution to this problem using nested fopen calls in different modes.
If pbooks is the FILE pointer to the binary file called book.dat. Then I did the following
FILE * pbooks;
if ((pbooks = fopen("book.dat", "r+b")) == NULL)
if ((pbooks = fopen("book.dat", "w+b")) == NULL)
So, initially, if the file doesn't exist, initial fopen function returns NULL and so inner fopen statement is executed and the file is created. When the file is already created and the program is executed again, initial fopen function is executed successfully and since the mode is r+b, the existing file is not truncated, so that we have access to the data which was entered earlier. I tested this and this is working. Please comment if this approach is recommended in practice.


Migrating from itext2 to itext7

Years ago, I wrote a small app in itext2 to gather reports on a weekly basis and concatenate them into one PDF. The app used com.lowagie.text.pdf.PdfCopy to copy and merge the PDFs. And it worked fine. Performed exactly as expected.
A few weeks ago I looked into migrating the application to itex7. To that end, I used the copyPagesTo method of com.itextpdf.kernel.pdf.PdfDocument. When run on the same file set, this produces warnings like:
WARN PdfNameTree - Name "section.1" already exists in the name tree; old value will be replaced by the new one.
When I click on the link to "section.1" in the first document of the merged PDF, I am taken to "section.1" of the last document. Not what I expected and not what happens when using the itext2 app. In the PDF's produced by itext2, if I click on the link to "section.1" of the first document in the combined PDF, I am taken to section 1 of the first document.
There is a hint in Javadocs for copyPagesTo saying
If outlines destination names are the same in different documents, all
such outlines will lead to a single location in the resultant
document. In this case iText will log a warning. This can be avoided
by renaming destinations names in the source document.
There is however, no explanation of how this should be done. I find it odd that this should be necessary in itext7, although it wasn't in itext2.
Is there a simple way to get around his problem?
I've also tried the Sejda desktop app and it produces correct results, but I would prefer to automate the process through a batch script.
My guess is iText 2 didn't even know it might be a problem.
If iText can't deduplicate destination names, the procedure is roughly:
Follow /Catalog -> /Names -> /Dests in each document to find the destination name tree.
Deduplicate the names, by adding suffixes. Remember that a name with a suffix added might be equal to an existing name in the same or another document. Be careful!
Now you can rewrite the destination name trees. Since you have only used suffixes, you can do this in place - the lexicographic ordering of the names is unaltered so the search tree structure is not broken.
Now, rewrite destination links in each PDF for the new names. For example any dictionary entry with key /Dest, or any /D in a /GoTo action.
Now, after all this preprocessing, the files will merge without name clashes.
(I know all this because I've just implemented it for my own PDF software. It's slightly hairy stuff, but not intractable.)
If you like, I can provide a devel version of cpdf with this functionality, if you would like to test it.

Automatically download emails from Outlook with SAS or Outlook rule

I am trying to create a program to automatically download the attached files that are sent to us from a certain email and then transform the delimiter with SAS, of those csv that are attached to us and pass those csv through a flow that I have already created.
I have managed to create a program that treats the csv as I want and the delimiter that I want, the problem is that when it comes to automating the download of files from Outlook it does not work.
What I have done is create a rule with the following VB code that I found on the internet:
Public Sub SaveAttachmentsToDisk(MItem As Outlook.MailItem)
Dim oAttachment As Outlook.Attachment
Dim sSaveFolder As String
sSaveFolder = "C:\Users\ES010246\Desktop"
For Each oAttachment In MItem.Attachments
oAttachment.SaveAsFile sSaveFolder & oAttachment.DisplayName
End Sub
I have changed the path to my personal path where i want the files are downloaded.
website: https://es.extendoffice.com/documents/outlook/3747-outlook
The problem is that this code does not work for me, it does absolutely nothing for me and no matter how much I search the internet, only this code appears.
Is there any other way to do with SAS what I want? What is it to automatically download 8 csv files sent to me by Outlook, or has someone experienced the same thing as me with VBA?
I have followed all the steps about 7 times so I think the error is not in copying the code or selecting certain options wrong, in fact I had copied and pasted the code and later I modified the path where I wanted those to be saved. files but it doesn't work, does anyone know why?
I will be tremendously grateful, thank you very much for everything!
First of all, you need to make sure the file name and path doesn't include forbidden symbols.
The VBA macro used for a rule in Outlook is absolutely valid except that a mail item may contain the attached files with the same name, so a file saved to the disk may be overwritten (saved with the same name). That's why I'd suggest generating a file name with your own unique IDs making sure that DisplayName property is not empty and has a valid name what can be used for file names (exclude forbidden symbols).
Also you may consider handling the NewMailEx event of the Application class which is fired when a new message arrives in the Inbox and before client rule processing occurs. Use the Entry ID returned in the EntryIDCollection string to call the NameSpace.GetItemFromID method and process the item. This event fires once for every received item that is processed by Microsoft Outlook. The item can be one of several different item types, for example, MailItem, MeetingItem, or SharingItem.
The Items.ItemAdd event can be helpful when items are moved to a folder (from Inbox). This event does not run when a large number of items are added to the folder at once.

Writing string to specific dir using chaquopy 4.0.0

I am trying a proof of concept here:
Using Chaquopy 4.0.0 (I use python 2.7.15), I am trying to write a string to file in a specific folder (getFilesDir()) using Python, then reading in via Android.
To check whether the file was written, I am checking for the file's length (see code below).
I am expecting to get any length latger than 0 (to verify that the file indeed has been written to the specific location), but I keep getting 0.
Any help would be greatly appreciated!!
import os.path
save_path = "/data/user/0/$packageName/files/"
name_of_file = raw_input("test")
completeName = os.path.join(save_path, name_of_file+".txt")
file1 = open(completeName, "w")
toFile = raw_input("testAsWell")
if (! Python.isStarted()) {
Python.start(new AndroidPlatform(this));
File file = new File(getFilesDir(), "test.txt");
Log.e("TEST", String.valueOf(file.length()));
It's not clear whether you've based your app on the console example, so I'll give an answer for both cases.
If you have based your app on the console example, then the code in onCreate will run before the code in main.py, and the file won't exist the first time you start the activity. It should exist the second time: if it still doesn't, try using the Android Studio file explorer to see what's in the files directory.
If you haven't based your app on the console example, then you'll need to execute main.py manually, like this:
Also, without the input UI which the console example provides, you won't be able to read anything from stdin. So you'll need to do one of the following:
Base your app on the console example; or
Replace the raw_input calls with a hard-coded file name and content; or
Create a normal Android UI with a text box or something, and get input from the user that way.

minifilter driver | tracking changes in files

What I'm trying to achieve is to intercept every write to a file and track the changes within the file. I want to track how much different the file content before and after the write.
So far in my minifilter driver I registered to IRP_MJ_WRITE callbacks and can now intercept writes to file. However I'm still not sure how can I obtain the content of the file before [preoperation] and the content after [postoperation].
The parameters that I have within the callback functions are:
PCFLT_RELATED_OBJECTS, PFLT_CALLBACK_DATA and I could not find anything related to the content of the file itself within these.
These are the operations that could change data in a file:
Modifying the file: IRP_MJ_WRITE, IRP_MJ_SET_INFORMATION ( specifically the FileEndOfFileInformation and FileValidDataLengthInformation information classes), IRP_MJ_FILE_SYSTEM_CONTROL ( specifically FSCTL_OFFLOAD_WRITE, FSCTL_WRITE_RAW_ENCRYPTED and FSCTL_SET_ZERO_DATA fsctl codes).
As for the content of the file itself that you just need to read it yourself.
If you mean the buffers as they are being written for example, check this out to find out more about the parameters of IRP_MJ_WRITE in the callback data. Esentially the buffer is at Data->Iopb->Parameters.Write.WriteBuffer/MdlAddress
Make sure you handle that memory correctly otherwise it will result a BSODs.
Good luck.

Open .mat file in matlab or unix - new user

I am going through someone's data analysis files (created in an older version of matlab) and trying to find out what a particular .mat file is that was used in a matlab script.
I am trying to load a .mat file in matlab. I want to see what is in it.
When I type...
load ('file.mat')
the file loads and I see two variables appear in the workspace. jobhelp and jobs.
When I try to open jobs by typing the following in the matlab command window...
the response is..
jobs =
[1x1 struct]
Does this mean that there is only a 1 x 1 structure in the .mat file? If so, how in the world do I see what it is? I'm even happy to load it in unix, but I don't know how to do that either. Any help would be greatly appreciated as I have a few files like this that I can't get any information from.
Again, a new user, so please make it simple.
It means that jobs is a cell array {} and within this cell array is a structure defined
To see the structure and its contents type jobs{1}
I think you are dealing with a SPM5 Batch-File. This variable is an image of the tree-like structure you can see in the Batch-Editor of SPM. Your job consists of one subitem (stats) which could have various subsubitems (like fMRI model specification, model estimation and so on).
To access this structure on the command line just proceed like Nick said:
Each level is a separate cell array that you can access with {#} after the name of the level. Example: jobs{1} shows you that there is a subitem named stats.
Subitems in structs are accessed with a dot. Example: jobes{1}.stats{1} shows you the subitems of the stats-entry.
Notice that there could be more than one entry on each layer: A stats module could (and probably would) contain various subitems. You can access them via jobs{1}.stat{2}, jobs{1}.stats{3} and so on.
The last layer would be the interesting one for you: The structures in here is an image of the options you can choose in the batch-editor.