Notes

There are 3 types of variables in Solidity

• local
  • declared inside a function
  • not stored on the blockchain
• state
  • declared outside a function
  • stored on the blockchain
  • global (provides information about the blockchain)

Code

Compile and deploy the code block below:

solidity
Variables.sol
Copy
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract Variables {
   // State variables are stored on the blockchain.
   string public text = "Hello";
   uint public num = 123;

   function doSomething() public {
       // Local variables are not saved to the blockchain.
       uint i = 456;

       // Here are some global variables
       uint timestamp = block.timestamp; // Current block timestamp
       address sender = msg.sender; // address of the caller
   }
}