#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>

typedef struct {
    int x;
    int y;
} Point;

void print_point(Point p) {
    printf("p.x == %d   p.y == %d\n", p.x, p.y);
}

int main(int argc, char* argv[]) {
    Point p1 = { .x = 5, .y = 6 };  // "NAMED INITIALIZER"  -- only for first assignment
    print_point(p1);                // that comes on the same line as declaration.

    Point p2 = p1;
    print_point(p2);

    // p1 = { .x = 7, .y = 9 }; // Named initializer does not work for a regular assignment.
    //                          // GCC:  "error: expected expression before ‘{’ token"

    // You can use a compound literal in much the same ways that you could use a variable
    // of that type, or a constant of a simple type (e.g., int, float, etc.).
    // 1. assignment (like ↑)
    // 2. pass to a function (useful for testing)
    // 3. initializing an object on the heap (for append(…) and other linked list stuff)
    //
    // Where possible:  Use compound literal to initialize objects on the heap, instead of
    // field-by-field.

    p1 = (Point) { .x = 7, .y = 9 };          // 1. assigning to a variable
    print_point((Point) { .x = 7, .y = 9 });  // 2. calling a function
    Point* a_p2 = malloc(sizeof(*a_p2));
    *a_p2 = (Point) { .x = 3, .y = 4 };       // 3. initializing object on heap

    // Not this:
    // a_p2 -> x = 3;
    // a_p2 -> y = 4;

    return EXIT_SUCCESS;
}
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