16.8 Constructing Array Values

You can construct an array from elements by writing them inside braces, and preceding all that with the array type’s designator in parentheses. There is no need to specify the array length, since the number of elements determines that. The constructor looks like this:

(elttype[]) { elements };

Here is an example, which constructs an array of string pointers:

(char *[]) { "x", "y", "z" };

That’s equivalent in effect to declaring an array with the same initializer, like this:

char *array[] = { "x", "y", "z" };

and then using the array.

If all the elements are simple constant expressions, or made up of such, then the compound literal can be coerced to a pointer to its zeroth element and used to initialize a file-scope variable (see File-Scope Variables), as shown here:

char **foo = (char *[]) { "x", "y", "z" };

The data type of foo is char **, which is a pointer type, not an array type. The declaration is equivalent to defining and then using an array-type variable:

char *nameless_array[] = { "x", "y", "z" };
char **foo = &nameless_array[0];