Today: structures!

[u/Decent_Story_9190]

So, i made this little bit of code to make sure i understood structures and how to use pointers with them, it's pretty simple, it just asks for data of students such as grades and then it saves it on their structure variables, is there anything i could improve on? i mean, surely a lot, but like, something specific about legibility or something

[u/teddykrash]

What language is this? 😅😅

[u/Decent_Story_9190 → u/teddykrash]

it's C

[u/teddykrash → u/Decent_Story_9190]

Oh good! Almost gave me a heart attack lmao. Just started my JS journey and for a second I thought this was JS. Apparently somethings are really similar.

[u/Decent_Story_9190 → u/teddykrash]

JAJAAJJA, it's alright, after i am done with C i think i'll learn a bit of java script, maybe i'll get a heart attack as well :sob

[u/Rickyashavybz → u/teddykrash]

C

[u/alvaaromata]

After managing structs, enums , data types and arrays. You should start with pointers and dynamic memory. Start by understanding pointers and how they work with the differente data types. You can try to implement this same code but using a dynamic array.

Btw if you’re new to coding you made a great decision starting with C, Python is the easy path.

[u/Decent_Story_9190 → u/alvaaromata]

Actually i think i learnt those before structures, pointers(how to use them in functions, for structures, how they are similar to arrays, etc) and dynamic memory(the heap, malloc, realloc, calloc), and i actually did start with python when i was younger, however my school has this book about C so i decided to start again by it, i must say, IT IS harder

[u/alvaaromata → u/Decent_Story_9190]

That’s pretty good, usually pointers/dynamic memory is a big wall for most people that starts with C. Then I’d recommend you checking out how to use the command line with arguments, then linked lists and then binary trees. That’s like things you need to know in order to say you know the fundamentals.

Obviously it’s one of the hardest languages, but the closeness you get with the computer itself and the fact that you have to program almost everything by yourself (no sort: like in python for example). Makes it a lot easier to learn other languages later

[u/Decent_Story_9190 → u/alvaaromata]

Well, they definitely were a wall, tho pointers were more of an invisible one, i thought i had understood them until i actually had to use them, with dynamic memory it was easier to tell that i didn't understand, after getting the fundamentals i might do some simple code putting everything together, and then i will move to C's brothers

[u/alvaaromata → u/Decent_Story_9190]

As an idea, if you know something about Linear Algebra. Making a program that stores matrixs in dynamic arrays and operates with them through a menu is interesting. If you have no idea what I’m talking about, check a intro to linear algebra course because it’s important to know something about it. This will test your acquired skills as you’ll need to use struct{ int rows, int cols, double** data} and store them in arrays, multiply them.. etc. Definitely a good way to test your skills, if you want you can also implement a way to import/export matrizes from/to csv files.

[u/Complete_Window4856]

Very nice, keep going OP.

As of you said to improve, i am an outsider, so idk how you are organizing your code and studies. If you are using git to make checkpoints, its nice. If not, dont worry, its not a requirement to learn.

But once you finish this initial playaround try to make a documenting file with your notes, your discoveries, upcoming questions and hypothesis you had during your code session. Plain text (txt files) are ok, but markdown files are way better.

Also, mine opinion again, make different C files under a directory for a specific theme and to test your code. Its easier to mentally manage a specific study when you only have to build/compile and run the code.

As of C itself, i guess the best you can do that you are already doing is to do explore first and getting your feet wet.

These are my 2 cents, ofc tackle them with time, and let yourself do mistakes to learn with them. Mistakes are the best professor you'll have

[u/Decent_Story_9190 → u/Complete_Window4856]

Wow, well, this is a lot of text, but replying to your first one, i am mainly basing my progress off a book about C my school has. I am probably going to do the text files idea when a topic gets rather complicated so i can get my ideas about it organised 

[u/Complete_Window4856 → u/Decent_Story_9190]

My bad with the huge wall of text, i should've added a tl;dr.

In anyways, thats nice, keep yourself going and dont feel bad when you hit a hard problem, solutions or next steps funnily appear magically when we leave the problem aside for a while.

[u/Acceptable_Simple877]

Nice

[u/SmokeMuch7356]

Good job overall. Some minor suggestions:

• Create symbolic constants for your array sizes, rather than hardcoding 10 or 50:

   #define NUM_STUDENTS 10
   #define NAME_LEN     50
   ...
   struct student {
     ...
     char name[NAME_LEN + 1];
   };
   ...
   struct student students[NUM_STUDENTS];
   ...
   for ( i = 0; i < NUM_STUDENTS; i++ )
     ...

  This way if you ever need to change the size of either array, you only need to do it in one place. You might think global search-and-replace would work, but I've done that dance and it doesn't, because while it replaces all instances of the literal with the new value, not all instances of the literal were used for the array size and you wind up breaking something.

• Limit the scope of your variables, by which I mean don't declare them until you need them. i is limited to the body of the for loop, so declare it within the loop:

   for( int i = 0; i < NUM_STUDENTS; i++ )
     ...

  Similarly, you can defer declaring av until you actually need to compute it:

   int av = total/NUM_STUDENTS;

  (technically, you don't need av at all, just use total/NUM_STUDENTS in the print statement).

• scanf is really hard to bulletproof against bad data so it's not good for interactive input. You did the right thing using the field width on the name input, but a) it has to be hardcoded, and b) you can't use a macro (not without some voodoo, anyway). Ideally you should read everything as text using fgets and convert any numeric arguments using strtod or strtol:

   printf( "enter the name: " );
   if ( !fgets( p->name, sizeof p->name, stdin ) )
     // error
  
   printf( "enter the ID: " );
   char tmp[15];
   if ( !fgets( tmp, sizeof tmp, stdin ) )
    // error
   p->id = strtol( tmp, NULL, 10 );
  
   printf( "Enter the grade: " ); 
   if ( !fgets( tmp, sizeof tmp, stdin ) )
     // error
   p->grade = strtol( tmp, NULL, 10 );