Gas Saving
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
一些节省燃气的技巧。
- 替换memory为calldata
- 将状态变量加载到内存
- 将 for 循环替换i++为++i
- 缓存数组元素
- 短路
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
// 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;
}
}