C error X is not a pointer; did you mean to use '.'-CodePudding

I am learning some C, and I have the following code, basically want I would like to do is to increase the size of people array in the for loop, but currently I receive an error. Could you please provide me a fix to my script with a brief explanation?

#include <stdio.h>

struct Person {
   int id;
};

struct State {
   struct Person people[0];
};

int main() {
    printf("Hello, world!");

    struct State state = {};

    for(int i = 0; i < 10;   i) {
      struct Person person = {};
      person.id = i;
      state->people[i] = person;
    }
  
    return 0;

Error I receive:

 clang-7 -pthread -lm -o main main.c
main.c:19:12: error: member reference type 'struct State' is not
      a pointer; did you mean to use '.'?
      state->people[i] = person;
      ~~~~~^~
           .
1 error generated.
exit status 1

CodePudding user response：

The error is pretty self-explanatory, given that you know what -> is used for: it is used when the struct (its left operand) is a pointer. It's equivalent to (*pointer_to_struct).. It does not matter what type the right operand of -> got.

You have no pointers to structs in your code so you can't use ->.

Also struct State state = {} is invalid C, an initializer list cannot be empty. You need to set at least one element, so for example you can do {0} and that will set everything in the struct to zero/null.