Structure in C++

Introduction to structure

Structure is a collection of data items of different data types grouped together under one name.
It is a user defined data type which stores related information together.
Structure is also know as a collection of variables under a single name.
The struct keyword is used to define structure.

Syntax:

struct struct_name
{
     member 1;
     member 2;
     .
     .
     member n;
};

Where,
     The struct keyword is required while defining the structure.
     The struct_name is the name given to the structure.
     The semicolon(;) should be used after the closing brace brackets.

Example

struct employee
{
     int empid;
     string empname;
     float salary;
};

Member Access Operator

Member Access Operator (.) is used to access any member of structure.
This operator is coded as a period between the structure variable name and the structure member.
The members of the structure can be accessed on an individual basis.

Syntax:
structure_variable_name.member;

Example : Demonstrating the structure declaration

#include<iostream>
using namespace std;
struct employee
{
    int empid=101;
    string empname="ABC";
    float salary=20000.0;
};
int main()
{
    employee e;       //There is now variable e of structure employee that has modifiable
    cout<<"Employee Id : "<<e.empid<<endl; // variables inside it.
    cout<<"Employee Name : "<<e.empname<<endl;
    cout<<"Employee Salary : "<<e.salary<<endl;
    return 0;
}

Output:
Employee Id : 101
Employee Name : ABC
Employee Salary : 20000

In the above example, a structure employee is defined which has three members: empid, empname, salary. Inside main() structure variable of e is defined and '.' operator is used to access the structure variables.
When structure is created, no memory is allocated.
It is only the blueprint for the creating of variables.
When structure is allocated, only required memory is allocated by the compiler.

Pointer to Structure

Structure can be pointed to by its own type of pointers.
A pointer to a structure can be used by the '&' operator.
Declarations of pointers to members are special cases of pointer declarations.

Example : Program demonstrating the pointer to structure

#include<iostream>
using namespace std;
int display(struct Employee * emp);
struct Employee
{
     int empid;
     string empname;
     float salary;
};
int main()
{
     Employee e;
     e.empid=101;
     e.empname="ABC";
     e.salary=20000.0;
     display(&e);
     return 0;
}
int display(struct Employee * emp)
{
     cout<<"Employee Id : "<<emp → empid<<endl;
     cout<<"Employee Name : "<<emp → empname<<endl;
     cout<<"Employee Salary : "<<emp → salary<<endl;
}