Non-zero Rule

Writing storage variables from 1 to 2 saves tremendous amount of gas, comparing to writing from 0 to 1. Or to put this to a more general rule, writing from non-zero to non-zer is much better than writing from zero to one.

Example

pragma solidity ^0.8.17;

uint256 varZero = 0;
uint256 varOne = 1;

function zeroToOne() external{
    varZero = 1; // This operation is gas-intensive
}
function oneToTwo() external{
    varOne = 2;  // This operation is far more gas-efficient
}

Calling function zeroToOne would cost 20022 gas and calling function oneToTwo sould cost 116 gas only, proving that altering from zero to one is about 172 times more gas-consuming than shifting from one to two.

Test Environment

• Compiler: solc 0.8.17
• Testing Framework: Foundry

ETH saved over 100 transactions

100 tx * 30 gwei * 0.000000001 * (20022-116) = 0.059718 ~= 0.06 ETH¹

USD Saved over 100 transactions

• At \$4000 / ETH: \$240
• At \$3000/ETH: \$180
• At \$2000/ETH: \$120