what is a struct in c 2b 2b

1
2#include <bits/stdc++.h>
3#include <iostream>
4
5#define ll long long
6
7using namespace std;
8
9struct student{
10	int roll;
11	string name;
12	int age;
13	
14	void studentDetails(){
15		cout<<"Name is "<<name<<" Age is "<<age<<" roll no is "<<roll<<endl;
16	}
17};
18
19
20int main(){
21	
22	student sumant;
23	sumant.roll = 30;
24	sumant.name = "Sumant Tirkey";
25	sumant.age = 18;
26	
27	sumant.studentDetails();
28	cout<<endl;
29
30    return 0;
31}

1struct Person
2{
3    char name[50];
4    int age;
5    float salary;
6};

1struct foo {
2  int bar;
3  foo() : bar(3) {}   //look, a constructor
4  int getBar() 
5  { 
6    return bar; 
7  }
8};
9
10foo f;
11int y = f.getBar(); // y is 3