cpp concatenate methods
string first_name { "Time" };
string second_name { "Machine" };
char first_n[100] = { "Hello" };
char second_n[100] = { "World" };
// METHOD 1: uses <string> header
cout << first_name + second_name << endl;
// METHOD 2: uses <cstring> header
cout << strcat(first_n, second_n) << endl;
// METHOD 3: uses <string> header
cout << first_name.append(second_name) << endl;