Question

In C:
How do you find the number of elements in an array of structs, after sending it to a function?

int main(void) {
  myStruct array[] = { struct1, struct2, struct3, struct4, struct5, struct6 };
  printf("%d\n", sizeof(array));
  printf("%d\n", sizeof(array[0]));
  f(array);
}
void f(myStruct* array) {
  printf("%d\n", sizeof(array));
  printf("%d\n", sizeof(array[0]));
}

For some reason the printf in main shows different results than the printf in f.
My need is to know how many elements are in the array.

Answer 1

You can’t.

You have to pass the size to the function, eg:

void f(myStruct* array, size_t siz);

Also notice that in f array is a pointer, while in main it is an array. Arrays and pointers are different things.