Arrays, structures, and unions

You initialize arrays and structures (at declaration time, if you like) with a brace-enclosed list of initializers for the members or elements of the object in question. The initializers are given in increasing array subscript or member order. You initialize unions with a brace-enclosed initializer for the first member of the union. For example, you could declare an array days, which counts how many times each day of the week appears in a month (assuming that each day will appear at least once), as follows:

int days[7] = { 1, 1, 1, 1, 1, 1, 1 }

The following rules initialize character arrays and wide character arrays:

You can initialize arrays of character type with a literal string, optionally enclosed in braces. Each character in the string, including the null terminator, initializes successive elements in the array. For example, you could declare

char name[] = { "Unknown" };

which sets up an eight-element array, whose elements are 'U' (for name[0]), 'n' (for name[1]), and so on (and including a null terminator).

You can initialize a wide character array (one that is compatible with wchar_t) by using a wide string literal, optionally enclosed in braces. As with character arrays, the codes of the wide string literal initialize successive elements of the array.

Here is an example of a structure initialization:

struct mystruct {

int i;
char str[21];
double d;

} s = { 20, "Borland", 3.141 };

Complex members of a structure, such as arrays or structures, can be initialized with suitable expressions inside nested braces.