• Lightfire228
    16·
    6 days ago

    The distinction is meaningless in the land of Opcode’s and memory addresses

    For example, a struct is just an imaginary “overlay” on top of a contiguous section of memory

    Say you have a struct

    struct Thing {
  int a;
  int b;
  Thing* child;
}

Thing foo {}

    You could easily get a reference to foo->child->b by doing pointer arithmetic

    *((*((*foo) + size(int)*2)) +size(int))

    (I’ve not used C much so I’ve probably got the syntax wrong)

    • bleistift2@sopuli.xyzEnglish
      1·
      5 days ago

      Yes, you can do crazy shit if you try hard enough, but every reasonable programmer would access foo->child->b als foo->child->b and not via that crazy LISPy expression.

      By question was: Why would you have a pointer to a memory address that itself only holds a pointer somewhere else?

      So far the only reasonable explanation is from @Victoria@lemmy.blahaj.zone:

      • arrays of function pointers
      • pass by reference of a pointer
      • Lightfire228
        1·
        5 days ago

        I’m more talking about theory than practical.

        I’ve not developed anything in C/C++, so I don’t know practical uses for a double pointer, aside from multidimensional arrays, or arrays of pointers

        My point was that, conceptually, pointers to pointers is how most complex data structures work. Even if the C representation of said code doesn’t have a int** somewhere