Application of array in data structure?
That rather depends on the underlying type. For any given type
T, an array of type T is user-defined if T is user-defined,
otherwise it is built-in. For example:
#include<string> // required to use std::string
std::string s[42]; // user-defined array
int i[42]; // built-in array
Here, s is a user-defined array because std::string is a
user-defined type, whereas i is a built-in array because int is a
built-in type.