Today I experienced cruelty of C and mercy of Sublime and SublimeLinter.

So yesterday I was programming late at night for my uni homework in C. So I had this struct:

typedef struct {
int borrowed;
int user_id;
int book_id;
unsigned long long date;
} entry;

and I created an array of this entry like this:

entry *arr = (entry*) malloc (sizeof(arr) * n);

and my program compiled. But at the output, there was something strange...

There were some weird hexadecimal characters at the beginning but then there was normal output. So late at night, I thought that something is wrong with printf statement and I went googling... and after 2 hours I didn't found anything. In this 2 hours, I also tried to change scanf statement if maybe I was reading the wrong way. But nothing worked. But then I tried to type input in the console (before I was reading from a file and saving output in a file). And it outputted right answer!!! AT THAT POINT I WAS DONE!!! I SAID FUCK THIS SHIT I AM GOING TO SLEEP.

So this morning I continued to work on homework and tried on my other computer with other distro to see if there is the same problem. And it was..

So then I noticed that my sublime lint has some interesting warning in this line
entry *arr = (entry*) malloc (sizeof(arr) * n);
Before I thought that is just some random indentation or something but then I saw a message: Size of pointer 'arr' is used instead of its data.

AND IT STRUCT ME LIKE LIGHTNING.

I just changed this line to this:
entry *arr = (entry*) malloc (sizeof(entry) * n);

And It all worked fine. At that moment I was so happy and so angry at myself.

Lesson learned for next time: Don't program late at night especially in C and check SublimeLInter messages.

Using an array of function pointers to replace large switch statements... holy shit.. I feel like Thanos getting the time stone.
Just when you think you can’t get your code to run any faster, nor did I think I could get the code any smaller... BOOM.. C never ceases to impress.

Next I’ll be turning this into “object” oriented ... but since it’s C ... it will just be Struct oriented .. SOP ..

What's the best way to null-terminate a struct array?

I need to tell you the story of my MOAB (Mother of all bugs).
I need to write some stuff in C (which i am fairly used to) and have a function that allocates memory for a Matrix on the heap. The matrix has a rows and columns property and an associated data array, so it looks like this
struct Matrix{
uint8_t rows;
uint8_t columns;
uint8_t data[];
}
I allocate rows*columns + 2 bytes of memory for it.
I also have a function to zero it out which does something like this
for(int i=0; i < rows*columns;i++){
data[i]=0;}

Let‘s come to the problem:
On my Mac the whole stuff works and passes all tests. We tried the code on a Linux machine and suddenly the code crashed in various places, sometimes a realloc got an invalid pointer, sometimes free got an invalid pointer and basically the code crashed at arbitrary points randomly.
I was confused af because did i really make THAT many errors?

I found out that all errors occured when testing my matrices so i looked more into it and observed it through the debugger.

Eventually i came to the function that zeroes out my matrix and it went unusually high and wondered if my matrix really was that big.
Then i saw it
The matrix wasn‘t initialised yet
It had arbitrary data that was previously in the heap.
It zeroed out a huge chunk of the heap space.
It literally wrote a zero to a shitload of addresses which invalidated many pointer.

You can imagine my facepalm