Soldity0.8-gas

Gas Saving Techniques
Some gas saving techniques.

Replacing memory with calldata
Loading state variable to memory
Replace for loop i++ with ++i
Caching array elements
Short circuit

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.13;

// gas golf
contract GasGolf {
// start - 50908 gas
// use calldata - 49163 gas
// load state variables to memory - 48952 gas
// short circuit - 48634 gas
// loop increments - 48244 gas
// cache array length - 48209 gas
// load array elements to memory - 48047 gas
// uncheck i overflow/underflow - 47309 gas

uint public total;

// start - not gas optimized
// function sumIfEvenAndLessThan99(uint[] memory nums) external {
// for (uint i = 0; i < nums.length; i += 1) {
// bool isEven = nums[i] % 2 == 0;
// bool isLessThan99 = nums[i] < 99;
// if (isEven && isLessThan99) {
// total += nums[i];
// }
// }
// }

// gas optimized
// [1, 2, 3, 4, 5, 100]
function sumIfEvenAndLessThan99(uint[] calldata nums) external {
uint _total = total;
uint len = nums.length;

for (uint i = 0; i < len; ) {
uint num = nums[i];
if (num % 2 == 0 && num < 99) {
_total += num;
}
unchecked {
++i;
}
}

total = _total;
}
}