Hello! I have a problem with importing CSV files in C.

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Hello. I would like to read a CSV file in C, but the program only reads the first 2 lines, after that it stops (I check this with a printf).
Imgur: The magic of the Internet[^]
Here my codes:GitHub - 420bela/help: h[^]
That file contains the actual code:excelbeolvas.c

What I have tried:

I have tried sscanf, but that code didnt work as well.

Posted 17-Nov-23 0:16am

420bela

Updated 17-Nov-23 3:31am

Andre Oosthuizen

v3

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Richard MacCutchan 17-Nov-23 6:46am

I expect there is something wrong in your code but it is impossible to guess where. You need to use the debugger to find out what is going on when you run the code. Also note, please post the relevant parts of your code and error details here in your question. Do not expect us to download code from other sites.

420bela 17-Nov-23 6:57am

Okey, can you suggest my a great debugger? I think you dont have to download my code, you can see in github.Excelbeolvas.c contains the import codes.

Richard MacCutchan 17-Nov-23 7:25am

No, I am not spending time on github. This is your third time of asking this question and unless you provide the information we ask for there is nothing we can do to help. As to using a debugger, the standard one built into Visual Studio will do everything you need.

420bela 17-Nov-23 7:36am

Sorry, but I have to use CodeBlocks.

Richard MacCutchan 17-Nov-23 7:38am

Check the documentation to see whether it has a built in debugger, or uses an existing one from Microsoft or GNU.

Rick York 17-Nov-23 14:57pm

If you have a decent connection you can download and use Visual Studio at no cost. You could use it and its debugger to make your program work and then move it back to CodeBlocks. That should work without issue.

CPallini 17-Nov-23 7:09am

The code you provided doesn't even compile. The first error is
bemenet.h: No such file or directory

420bela 17-Nov-23 7:12am

I only uploaded the files that I needed for the scan.

CPallini 17-Nov-23 7:21am

So, I cannot test your code.

420bela 17-Nov-23 7:37am

You are right, here are all the codes: https://github.com/420bela/fully.git

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Richard MacCutchan · Accepted Answer · 2023-11-17T01:36:00

Solution 1

OK, I have had a look at your code, and you have a number of lines like the following:

strncpy(uj->kerdes, strtok(NULL, ";"), sizeof(uj->kerdes) - 1);

So if there is a field missing in the csv your code will crash, as the call to strtok will return NULL. You need to change your code to call strtok first, and check whether it actually returns a token. Other than that, the problem could be anywhere in the remaining code.

Posted 17-Nov-23 1:36am

Richard MacCutchan

Comments

420bela 17-Nov-23 7:45am

The CSV contains no missing parts. All parts of all rows contain data with the appropriate structure.

Richard MacCutchan 17-Nov-23 7:54am

Fine, but you still need to find out where the program crashes, and provide full details of what is happening at that point. We cannot do that for you.

420bela 17-Nov-23 8:01am

How can I find out? I really don't mean to be obtuse, but this is the first time I've done a scan or a longer programme.

Richard MacCutchan 17-Nov-23 8:54am

As I said, you use the debugger and step through the code. Or if that is too complicated, then you need to add more print statements to show what progress is being made. There is no simple universal rule for this, as each program is unique. It starts with finding the general area that the code is failing, and then by further iterations, narrow it down to the exact statement and the data that (possibly) causes the failure.

Richard MacCutchan 17-Nov-23 9:42am

I have a suspicion that the problem is somewhere around the following function:

void hozzafuz(Kerdesek*eleje, Kerdesek* uj){

in file beolvas.c. At the very least it is worth checking that the pointers you are passing around are all valid.

Dave Kreskowiak 17-Nov-23 9:56am

You MUST learn debugging techniques and the use of debuggers to solve this. If you don't do this, you will always struggle to write code for the rest of your life.

Debugging exists to debug YOU, not the code. It's a tool used to help you understand what the code is doing and what the code is seeing in the way of data. It corrects YOUR understanding of the code so you can make changes and write better code.

Andre Oosthuizen 17-Nov-23 9:34am

+5 for the pure effort of going to GitHub to check the code!

Richard MacCutchan 17-Nov-23 9:40am

Thanks, but my lack of knowledge of Hungarian hekd me back a bit.

Andre Oosthuizen 17-Nov-23 12:54pm

:)

merano99 · Accepted Answer · 2023-11-17T12:44:00

As others have already written, this is now the third question. I have already offered some solutions. Unfortunately so far without feedback or stars.

Here are the contributions so far:

Hello! I have problems with importing CSV files in C.
https://www.codeproject.com/Questions/5372509/Hello-I-have-problems-with-importing-CSV-files-in
https://www.codeproject.com/Questions/5372504/Hello-I-have-problems-with-importing-CSV-files-in

Various headers are missing, but these can be ignored for the time being, as the program will crash beforehand.

C

// #include "bemenet.h"
// #include "dicslist.h"
// #include "idoszam.h"

Calling the "appendQuestion" function at the end of "readCSV"

C

void csvBeolvas(const char *fajlnev, Kerdesek **fej) 
// void readCSV(const char* filename, Questions** head)
{
  ...
  
  // appendQuestion(head, newQuestion) 
  hozzafuz(fej, uj);
}

should actually cause the compiler to issue a warning, as the function hozzafuz has unsuitable parameters and will not work.
Of course, the hozzafuz function should be protected against null pointers and you should also also think about what should happen if the list is still empty.