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//en.cppreference.com/w/c/language/compound_literal.html
#include <stdio.h>
int *p = (int[]){2, 4}; // creates an unnamed static array of type int[2]
// initializes the array to the values {2, 4}
// creates pointer p to point at the first element of
// the array
const float *pc = (const float []){1e0, 1e1, 1e2}; // read-only compound literal
struct point {double x,y;};
int main(void)
{
int n = 2, *p = &n;
p = (int [2]){*p}; // creates an unnamed automatic array of type int[2]
// initializes the first element to the value formerly
// held in *p
// initializes the second element to zero
// stores the address of the first element in p
void drawline1(struct point from, struct point to);
void drawline2(struct point *from, struct point *to);
drawline1(
(struct point){.x=1, .y=1}, // creates two structs with block scope and
(struct point){.x=3, .y=4}); // calls drawline1, passing them by value
drawline2(
&(struct point){.x=1, .y=1}, // creates two structs with block scope and
&(struct point){.x=3, .y=4}); // calls drawline2, passing their addresses
}
void drawline1(struct point from, struct point to)
{
printf("drawline1: `from` @ %p {%.2f, %.2f}, `to` @ %p {%.2f, %.2f}\n",
(void*)&from, from.x, from.y, (void*)&to, to.x, to.y);
}
void drawline2(struct point *from, struct point *to)
{
printf("drawline2: `from` @ %p {%.2f, %.2f}, `to` @ %p {%.2f, %.2f}\n",
(void*)from, from->x, from->y, (void*)to, to->x, to->y);
}