A [3] = "ABC"

12.23 A [3] ="ABC"; Is it legal? What does it mean?

Although useful only in extremely limited environments, it is legal in ansi c (which may include some systems earlier than ANSI. It declares an array with a length of 3 and initializes its three characters to 'A', 'B', and 'C', but it does not have the usual'/0'Character. Therefore, this array is not a real C string and cannot be used in strcpy, printf % s, etc.

Most of the time, you should ask the compiler to calculate the number of initial values for Array initialization. In the initial value ''abc ", the calculated length is of course 4.