How to implement a hash table in C (2021)

I find that stuff enjoyable. I almost never use malloc, I learnt to use calloc so it's my go-to allocator.

Whenever I write an allocation I try to write a free after it, then fill in the code in between.

Use of static analysers and sanitisers helps too.

Like some people enjoy making all their hand tools from scratch in their workshop, there's a craft and discipline to follow and a satisfaction in doing things well, I enjoy the craft of and discipline C for the same reason.

Actually, that is UB.

> If the result is not representable in an object of that type, the behavior is undefined. In other words, if the expressions P and Q point to, respectively, the i-th and j-th elements of an array object, the expression (P)-(Q) has the value i - j provided the value fits in an object of type ptrdiff_t.

Well, but what if you're working with a 16-bit microcontroller? Apparently, there were quite some heated discussions about that which is why, while size_t was required to be at least 16 bits, ptrdiff_t was required to be at least 17 bits, in C99... and then it was reverted back to 16 bits in C23. See e.g. [0]

This trade-off is actually making me sad. One can either have all the sizes and offsets fit into (unsigned/signed) integers, or one can have objects spanning more than half of the memory space. I think for my language I'd pick "all sizes/offsets are signed, and so yeah, you can't span all of the memory with a single char array".

[0] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2808.htm

From my experience, learning a language like C goes beyond what you cover in University. Either that or the one I went to was **.

I remember back in the late 90s to early 00s, I had fun countering OOP guys claiming C "cannot do XYZ" - but it obviously can.. the C way.

For method override, my mind was blown when I discovered function pointers!

It was my "Wait. What?" moment.. along with various other things!

Below is sample code (not tested)

  // generic monster "class"
  struct monster_t {
    int health;
    struct weapon_t *weapon;
    // etc..

    void (*attack)(struct monster_t *self);   // our function pointer
    // more function pointers for update, die, hit, etc...
  };

  // impl
  void monster_notassigned_attach(struct monster_t *monster) {  // safety net (todo)
    printf("Attack not assigned to monster...\n");
  }

  void monster_dragon_attack(struct monster_t *monster) {
    // attack for dragon
    printf("Dragon is attacking you...\n");
  }

  void monster_wizard_attack(struct monster_t *monster) {
    // attack for wizard
    printf("Wizard is attacking you...\n");
  }


  // creation
  void monster_dragon_create(struct monster_t *monster) {
    // allocate, then assign.. and do...
    monster->attack = monster_dragon_attack;
  }

  void monster_wizard_create(struct monster_t *monster) {
    // allocate, then assign.. and do...
    monster->attack = monster_wizard_attack;
  }
  
  void main() {
    // testing...
    struct monster_t monsters[10];       // can store various monsters!
  
    monster_dragon_create(&monsters[0]);
    monster_wizard_create(&monsters[1]);  

    for(int i = 0; i 

Not suggesting I support or follow the above especially for games. It is just a proof of concept! I always tell people that coding in C (or any non-OOP language) should not be done the way you would in Java, C#, etc. As mentioned, the above is a demonstration.