Hello! I have problems with importing CSV files in C.

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First of all, I apologise if I'm bothering anyone with my incessant "similar" questions, but unfortunately the update to my last question was only accepted after 7 days.
I still have the same problem as before: I want to read a CSV into a linked list. I changed my code since my previous question, so I made another "post".

The whole program consists of 2 parts: in one module I create the linked list and 3 functions: the first:Meg gets the corresponding data and returns a concatenated list type element. The second:Appends an element to the concatenated list (no return value). The third:Helps to unlock the concatenated list.And in main, I import the CSV file using the created functions with more or less success.

When the program runs, it does not print anything, not even the basic stuff(Process returned 0 (0x0) execution time : 0.021 s
Press any key to continue.)

There is the my code:
GitHub - 420bela/import: csv[^]

I haven't set up the accented letters yet, but I don't think that should cause an error.

What I have tried:

This is about my third solution "idea" but so far none of them have worked :(

Posted 18-Nov-23 0:12am

420bela

Updated 18-Nov-23 0:37am

Andre Oosthuizen

v2

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Andre Oosthuizen 18-Nov-23 6:43am

Going into question 4 with same issue should have shown you by now what we require to really help you solve this. You cannot just give a link to a bunch of files and code hoping that we will open these to assist you, most of us do not open unknown links at all.

If we do open and view your files on Github, verry little of us will actually spend the time to read through numerous lines of code to try and see where your app is faulty.

The best way to get a proper answer is to post the code that you have (not all of your code as we will not read through hundreds and thousands lines of code either) where the error occurs, post the actual errors or issue with as much information as possible. That way we can understand and then try and solve it with you.

The quicker you follow this, the quicker you will probably have a solution.

Also be more specific with your issue as "It does not work" does not help us at all or make sense to us.

420bela 18-Nov-23 7:23am

I understand, but what can you write other than that it doesn't work? I did a "test" to see if the linked list works at all. This code will print the data correctly.#include <stdio.h>
#include <stdlib.h>
#include "bevas.h"

int main()
{

Adatok* adat1 = ujelem(1, "MIZU?", "Aa", "Bb", "Cc", "Dd", 'A', "TORI");
hozzafuz(adat1, ujelem(1, "MIZUss?", "Aab", "Bbc", "Ccd", "Dde", 'B', "TOeRI"));

Adatok* jelen = adat1;
while (jelen != NULL) {
printf("%d, %s, %s, %s, %s, %s, %c, %s\n",
jelen->nehezseg,
jelen->kerdes,
jelen->A,
jelen->B,
jelen->C,
jelen->D,
jelen->valasz,
jelen->kategoria);

jelen = jelen->kovetkezo;
}

// Free the allocated memory
felszabadit(adat1);

return 0;
}
When I want to read from a file, it doesn't work (printf doesn't print anything) and probably doesn't include it in the list
#include <stdio.h>
#include <stdlib.h>
#include "bevas.h"

int main()
{

int nehezseg=1;
char kerdes[100]="valami";
char A[20]="valami";
char B[20]="valami";
char C[20]="valami";
char D[20]="valami";
char valasz='C';
char kategoria[20]="valami";

Adatok *elso = ujelem(nehezseg, kerdes, A, B, C, D, valasz, kategoria);
Adatok *jelen;
FILE* fp=fopen("C:\\Users\\Zephyrus\\Desktop\\kerdes.csv","r");
if(fp==NULL ){
printf("HIBA:Nem tudtam megnyitni a fajlt");
}

while(fscanf(fp," %d;%s;%s;%s;%s;%s; %c;%s",&nehezseg,kerdes,A,B,C,D,&valasz,kategoria)!=EOF){
hozzafuz(elso,ujelem(nehezseg,kerdes,A,B,C,D,valasz,kategoria));
}
fclose(fp);

jelen=elso->kovetkezo;
while(jelen!= NULL){
printf("%d,%s,%s,%s,%s,%s,%c,%s\n",
jelen->nehezseg,
jelen->kerdes,
jelen->A,
jelen->B,
jelen->C,
jelen->D,
jelen->valasz,
jelen->kategoria);
jelen=jelen->kovetkezo;
}
felszabadit(elso);

return 0;
}
The first few lines of the source file:
1;Hol található a csarnokvíz?,a pályaudvaron;a szemben;a tejcsarnokban;barlangfürdőben;B;BIOLÓGIA
1;Melyik járműről elnevezett együttes tagja volt Zorán a 60-as években?;Villamos;HÉV;Autóbusz;Metró;D;ZENE

3 solutions

Solution 2

see:
Hello! I have a problem with importing CSV files in C.[^]

Posted 18-Nov-23 1:00am

merano99

Comments

420bela 18-Nov-23 7:14am

The current code is not exactly the same as the previous ones

merano99 18-Nov-23 7:54am

But the problems and my answers to them are the same. To be honest, I am shocked that the source code has regressed compared to the previous 3 versions. The source code is not even compilable. Instead of the discussed function for reading the (Hungarian) CSV file, fscanf is still used.
In addition, Kerdesek (Questions) was unnecessarily renamed to Adatok (Data). At least under Windows, reading the Hungarian CSV file with char strings does not work. Strings are unnecessarily copied several times without checking the length. In addition, there are many sprintf(), although you could simply copy strings with strncpy(). I had already noted that Hungarian special characters will probably not fit well in a char-string, but this is still being tried.

Solution 3

OK, I see what is wrong - the most annoying and useless C function ever invented: scanf!

Change the scan loop to the following:

C++

char buffer[256];
while (fgets(buffer, sizeof buffer, fp) != NULL)
{
    sscanf(buffer, "%d;%s;%s;%s;%s;%s;%c;%s", &nehezseg, kerdes, A, B, C, D, &valasz, kategoria);
    hozzafuz(elso,ujelem(nehezseg,kerdes,A,B,C,D,valasz,kategoria));
}

Posted 18-Nov-23 1:55am

Richard MacCutchan

Comments

420bela 18-Nov-23 8:04am

Thanks, now it's running. Unfortunately, it is still not good.The "nehezseg" is read well. But then the "kerdes" is not good, it only reads the first space. The rest is the "valami" at the beginning.
It says:
1,Hol,valami,valami,valami,valami,C,valami
1,Melyik,valami,valami,valami,valami,C,valami
1,Hogy,valami,valami,valami,valami,C,valami
1,Hol,valami,valami,valami,valami,C,valami
1,Hogyan,valami,valami,valami,valami,C,valami

Richard MacCutchan 18-Nov-23 8:13am

Well I have done enough work on this problem, now it is your turn to learn how to debug your code.

420bela 18-Nov-23 9:12am

Understandable. Thanks for your help. Can you recommend a good debugger? Or maybe you didn't interpret your answer correctly. I'm not perfect in English. Did you mean, should I try to figure out the error on my own or use a debugger

Richard MacCutchan 18-Nov-23 9:18am

Your English is fine, my Hungarian does not exist.

Here is a link to the Code::Blocks page that mentions the debugger: Features - Code::Blocks[^]. I have not used that system so I do not know how easy it is. My recommendation would be to switch to Visual Studio 2022 Community Edition – Download Latest Free Version[^], which has a built in (very powerful) debugger. It is simple to use and shows you the content of any and all variables at each step in the code.

420bela 22-Nov-23 12:03pm

Should I download visual studio or visual studio code? I'm sorry I'm writing now, but I haven't had the time, but now I'd like to finish my work.

Richard MacCutchan 22-Nov-23 12:23pm

Just use the Download link in my previous comment, to download Visual Studio Community, which is a free edition.

420bela 22-Nov-23 12:26pm

Okay, I downloaded it. Now what? I have to choose which "workloads" to download.

Richard MacCutchan 22-Nov-23 12:31pm

You will want the C++ workload "Desktop Development with C++".

420bela 22-Nov-23 12:57pm

Thanks, I think I could open it. I got this error code: 'strcpy': This function or variable may be unsafe. Consider using strcpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS
What can I do ?

420bela 22-Nov-23 13:06pm

I managed to turn it off, now the program runs, but it doesn't print anything to the screen. It is very interesting to me that I ran the same code and 2 programs printed differently (one of them nothing)

420bela 22-Nov-23 13:20pm

Should I use Local Windows Debugger?

Richard MacCutchan 22-Nov-23 13:33pm

Yes. As I said below, in the text window of your source code, click the border, so it sets a breakpoint on that line. Press F5 and the program will run to that point. You can then single step by pressing F10, and examine variables at each point.

420bela 22-Nov-23 13:36pm

I have that set, but it throws an error in the other module: exception thrown: Exception thrown: write access violation.
uj was 0xFFFFFFFFC2287A40.
Is it good if I get this, I mean something like this is how the debugger works or am I doing something wrong?

Richard MacCutchan 23-Nov-23 3:42am

Well, it is good in the sense that you can see that something is wrong with the value of uj. That number looks like a stack address so you now need to work backwards to find out where it was set, and why the value is wrong.

merano99 18-Nov-23 10:46am

I had pointed out to you several times that Hungarian special characters do not fit well in a char-string.

Richard MacCutchan 18-Nov-23 10:58am

I think that is the least of his concerns.

420bela 18-Nov-23 11:20am

Yes, I've already solved the Hungarian special characters issue, but thanks for the warning!
P.S. What exactly do I need to download within visual studio? I suddenly couldn't find a C language section.Or is it the default in the program?

Richard MacCutchan 18-Nov-23 11:34am

There is no section specific to C, but the C++ section will create programs from C source code.

420bela 18-Nov-23 11:39am

So I'll just install it and it will include the debugger as well?

Richard MacCutchan 18-Nov-23 12:11pm

Yes. You just need to create a new project, add your files and build the code. You then click your mouse in the left hand border where you want to start debugging, and it will mark the line to show it is a breakpoint. Press F5 on the keyboard and the program will start, and then stop in the debugger at the first breakpoint. You can then step through the code line by line by pressing F10. Each time it stops you can hover your mouse over any variable name and it will show you what the variable contains. It really is that simple.

420bela 22-Nov-23 12:37pm

I sould select "Attach to Process"

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Richard MacCutchan · Accepted Answer · 2023-11-18T00:59:00

We have given you a number of suggestions to find out why your code is not working. The most important one that you seem to ignore, is to get the maximum error messages from the compiler. Your main.c element has the following:

C++

while(fscanf(fp," %d;%s;%s;%s;%s;%s; %c;%s",&nehezseg,kerdes,A,B,C,D,valasz,kategoria)!=EOF){
    hozzafuz(elso,ujelem(nehezseg,kerdes,A,B,C,D,valasz,kategoria));
}

and my compiler correctly noted that the parameter for a %c type, should be a pointer to a character variable, rather than the name. So change that to:

C++

while(fscanf(fp," %d;%s;%s;%s;%s;%s; %c;%s",&nehezseg,kerdes,A,B,C,D,&valasz,kategoria)!=EOF){
    hozzafuz(elso,ujelem(nehezseg,kerdes,A,B,C,D,valasz,kategoria));
}

And get rid of most of the lines in your .csv file; until your code works there is no point trying to process hundreds of lines, just use a few samples.

Other than that you need to do what we told you yesterday, and start using the debugger.

Hello! I have problems with importing CSV files in C.

3 solutions

Solution 1

Solution 2

Solution 3

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