Page 120 - C-Language

int *p = (int [2]){ 2, 4 };

p is initialized to the address of the first element of an unnamed array of two ints.

The compound literal is an lvalue. The storage duration of the unnamed object is either static (if
the literal appears at file scope) or automatic (if the literal appears at block scope), and in the latter
case the object's lifetime ends when control leaves the enclosing block.

void f(void)
{
int *p;
/*...*/
p = (int [2]){ *p };
/*...*/
}

p is assigned the address of the first element of an array of two ints, the first having the
value previously pointed to by p and the second, zero.[...]

Here p remains valid until the end of the block.

Compound literal with designators

(also from C11)

struct point {
unsigned x;
unsigned y;
};

extern void drawline(struct point, struct point);

// used somewhere like this
drawline((struct point){.x=1, .y=1}, (struct point){.x=3, .y=4});

A fictive function drawline receives two arguments of type struct point. The first has coordinate
values x == 1 and y == 1, whereas the second has x == 3 and y == 4

Compound literal without specifying array

length

int *p = (int []){ 1, 2, 3};

In this case the size of the array is no specified then it will be determined by the length of the
initializer.

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