Contract to demo reference typed data types in Solidity

DemoReferenceTypes.sol

// Solidity program to demonstrate
// reference types
pragma solidity ^ 0.8.5;  
  
// Creating a contract
contract DemoReferenceTypes {
   // Defining an array of fixed size  
   uint[5] public fixedSizeArray = [uint(1), 2, 3, 4, 5];
    
   // Defining a Structure
   struct DemoStruct {
       string firstVar;
       address secondVar;
       uint8 thirdVar;
   }
 
   // Creating a structure object
   DemoStruct public struct1;
  
   // Creating a mapping
   mapping  (address => DemoStruct) public sampleMapping;
   
   address[] student_result;
 
   constructor() {
     struct1.firstVar = "abcd";
     struct1.secondVar = address(0x0);
     struct1.thirdVar = 1;
     sampleMapping[address(0x10)] = struct1;
  }
}