Block and transaction global variables

Solidity provides access to a few global variables that are not declared within contracts but are accessible from code within contracts. Contracts cannot access a ledger directly. A ledger is maintained by miners only; however, Solidity provides some information about the current transaction and blocks to the contracts so that they can utilize them. Solidity provides both block- and transaction-related variables.

The following code illustrates examples of using global transaction, block, and message variables:

// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.9.0;
contract TransactionAndMessageVariables {
    event logstring(string);
    event loguint(uint);
    event logbytes(bytes);
    event logaddress(address);
    event logbyte4(bytes4);
    event logblock(bytes32);
    
  ...