The structure is a collection of variables of different data types under a single name in c++. It is similar to a class in that, both hold a collection of data of different data types.
Each variable in the structure is known as a member of the structure.

a structure can contain many different data types (int, string, bool, etc.).
To create a structure, use the struct keyword and declare each of its members inside curly braces.
Declaration of Structure :
Two types of Declaration of Structure in c++ :
1) Declaration with variable
struct student // Structure declaration
{
int roll_no; // Member (int variable)
string address; // Member (string variable)
} s1; // Structure variable2) Declaration without variable
struct student // Structure declaration
{
int roll_no; // Member (int variable)
string address; // Member (string variable)
};
void main()
{
student s1; // Structure variable by using student structure name
}Also Read This :- 2d array in c++
Example of Structure :
#include<iostream>
#include<conio.h>
using namespace std;
struct student {
  int roll_no;
  string name;
  string address;
};
int main() {
  // Create a student structure and store it in s1;
  student s1;
  s1.roll_no = 101;
  s1.name = "ABC";
  s1.address = "Palanpur";
  // Create another student structure and store it in s2;
  student s2;
  s2.roll_no = 102;
  s2.name = "XYZ";
  s2.address = "Sidhpur";
  // Print the structure members
  cout << s1.roll_no << " " << s1.name << " " << s1.address << "n";
  cout << s2.roll_no << " " << s2.name << " " << s2.address << "n";
  return 0;
}output
101 ABC Palanpur 102 XYZ Sidhpur