Structure is a user-defined data type where it allows you to combine data of different data types. In a way, Structures are similar to arrays but the difference is in type of the data. Arrays is a collection of similar data but structures combine different types of data.

How to define a structure

struct keyword is used to define a structure.

struct structure_name {

   member definition;
   member definition;
   ...
   member definition;
} [one or more structure variables]; 

How to declare structure variables

Structure variables can be declared in two ways.

1. Declaring variables seperately from its definition.

[struct] structure_name variable name;

2. Declaring variables along with definition(this method is not recommended)

struct structure_name {

   member definition;
   member definition;
   ...
   member definition;
} one or more structure variables; 

Example

// structure definition
struct mobile {
    char model[30];
    char brand[30];
    int cost; 
}

// Declaring variables seperately from its definition

mobile m1, m2;

//Declaring variables along with definition

struct mobile {
    char model[30];
    char brand[30];
    int cost; 
}m1, m2;

How to access structure members

You can access the structure member using variable_name.membername

Example

#include <iostream>
using namespace std;

struct mobile {
    string model;
    string brand;
    int cost; 
};


int main()
{
  mobile m1;
  m1.brand = "Apple";

  // display the value of structure variable and accessing structure variable - brand
  cout << "Brand of the mobile: " << m1.brand;
    
  return 0;
}

Check result here

Difference between C structures and C++ structures

C Structures	C++ Structures
Member functions are not allowed inside structures	Member functions are allowed inside structures
Direct initialization of members are not possible	Direct initialization of memebers can be done
struct keyword is compulsory to declare structure variables	struct keyword is not required to declare structure variables
Constructor can't be present in structures	Can have constructor in structure
Can not have static members	Can have static members