User defined data types in c++(Structure and Union)

               Basically, the data types are categorised into two types. One is the primitive data types supported by programming language. Another one is user defined datatypes which is created by the user.

Some the user defined datatypes in c++ are given below.

• ·       Structures
• ·       Unions

Let us implement each one of this.

Structures:

              It is one of the user defined data types in c++, which has collection of members of different datatypes.

Syntax:

Creating a structure:

 Structure structure_name {

                Data type data_member1;

                Data type data_member2;

                ………………………………………

                Data type data_membern;

                }

Variable creation:

              The structure variable is created by as follows..

   Structure_name variable_name;

To assign values: Structure_name variable_name= {value1,value2,…….,valuen};

To access variables: structure_name.value1;

C++ Sample Code:

#include <bits/stdc++.h>

using namespace std;

// Define structure

struct student {

    int id;

    char name[20];

    char s_class[3];

};

int main() {

        // Two objects are created and assigned with value

    student s1 = {1, "Ajay","I"};

    student s2 = {2, "Jey", "II"};

    // Print the values

    cout << s1.id <<" "<<s1.name <<" " <<s1.s_class<< endl;

    cout << s2.id <<" "<<s2.name <<" " <<s2.s_class<< endl;

    return 0;

}

Output:

1 Ajay I

2 Jey II

Unions:

              This is another user defined data structures in which data members share the total memory of union.

The structure and union are similar,only different is the memory space.

Syntax:

Union union_name {

                                    Datatype data_member1;

                                    Datatype data_member2;

                                    ……………………………………..

                                    Datatype data_membern;

                                 }

Object creation: union_name variable_name;

Accessing the object: variable_name. data_member;

C++ sample Code:

#include <bits/stdc++.h>

using namespace std;

// Define union

union student {

    int id;

    char s_class;

};

int main() {

        // Two objects are created and assigned with value

    student s1;

    s1.id = 1;

    cout<<"Id:" <<s1.id <<endl;

    s1.s_class = 'I';

    cout << "Class:" <<s1.s_class<<endl;

    cout << s1.id <<" "<<s1.s_class<< endl;

    return 0;

}

Output:

Id:1

Class:I

73 I

Here, the memory is restricted. So, the id is printed a ascii value of ‘I’.

These are the user defined data types structures and unions. Hope ,you understood the syntax and coding samples. Keep Coding!!!