examples/solidity-require-statements

RequireStatements.sol

pragma solidity >=0.5.0;

contract RequireStatements {

    function someFunction(address _anAddress) external {
        // Require that the address given as a parameter is not equal to an empty addess.
        // If the address is empty, the whole transaction will not be completed and will be reverted
        require(_anAddress != address(0), "Not a valid address");
        ...
    }
}