There are two kind group of data type that needed to reserve amount memory, primitive data and user-defined data. Primitive data just like Int (4 byte), Char (1 byte), Double (8 byte) and so on. But what about we construct our custom data types, like a new data type that contains Int and Char? Then this is called user-defined data.
Basically, we just gathering two or more primitive data into one new data type. For instance, first we have Customer and Grade variable:
1 2 | int customer; string address; |
Because Customer and Grade tight each other, we construct a new data type called “user” that contains Customer and Grade. To do this step in C++, we use “struct” :
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | #include<iostream> #include<string> using namespace std; struct data_t { int customer; char grade; } user; int main() { user.customer = 1; user.grade = "A"; cout << insurance.customer; cout << insurance.grade; return 0; } |
Now, we have an example of user-defined data called “user”. In memory level, it will reserve amount of memory that summary of this two primitive data type which int is 4 byte and char is 1 byte. In another programming language like Pascal, this kind of data called as “record”.