#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
#pragma pack(1)

typedef struct {
    char label;  // on our platform, sizeof(char) == 1
    int x;       // on our platform, sizeof(int)  == 4
    int y;       // "  "   "         "            "  "
} Point;

typedef union {
    int   as_int;      // on our platform, sizeof(int) == 4
    char* as_string;   // on our platform, sizeof(▒▒*) == 8
} IntOrString;         // on our platform, sizeof(IntOrString) == 8
                       //   --- max of the sizes of each element in the union

int main(int argc, char* argv[]) {

    int n = 5;
    printf("sizeof(n) == %zd\n", sizeof(n));
    printf("sizeof(int) == %zd\n", sizeof(int));  // don't use sizeof(TYPE)
    printf("sizeof n == %zd\n", sizeof n);
    //printf("sizeof int == %zd\n", sizeof int); // error: expected expression before ‘int’
    
    Point p = { .label = 'A', .x = 5, .y = 7 };
    printf("sizeof(p) == %zd\n", sizeof(p));  // 9 bytes .... but only with #pragma pack(1)

    IntOrString int_or_string = { .as_int = 4 };
    printf("sizeof(int_or_string) == %zd\n", sizeof(int_or_string));

    int_or_string = (IntOrString) { .as_string = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" };
    printf("sizeof(int_or_string) == %zd\n", sizeof(int_or_string));

    return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */