Platform: Code4rena
Start Date: 07/07/2022
Pot Size: $75,000 USDC
Total HM: 32
Participants: 141
Period: 7 days
Judge: HardlyDifficult
Total Solo HM: 4
Id: 144
League: ETH
Rank: 131/141
Findings: 1
Award: $37.47
🌟 Selected for report: 0
🚀 Solo Findings: 0
🌟 Selected for report: joestakey
Also found by: 0x1f8b, 0x29A, 0xA5DF, 0xKitsune, 0xNazgul, 0xNineDec, 0xalpharush, 0xkatana, 0xsanson, 0xsolstars, 8olidity, Avci, Bnke0x0, BowTiedWardens, Chom, Deivitto, ElKu, Fitraldys, Funen, IllIllI, JC, Kaiziron, Lambda, Limbooo, MEP, NoamYakov, PwnedNoMore, RedOneN, ReyAdmirado, Rohan16, Ruhum, Saintcode_, Sm4rty, TomJ, Tomio, TrungOre, Tutturu, Waze, _Adam, __141345__, ajtra, apostle0x01, asutorufos, benbaessler, brgltd, c3phas, codexploder, cryptphi, delfin454000, dharma09, djxploit, durianSausage, fatherOfBlocks, giovannidisiena, gogo, horsefacts, hrishibhat, hyh, ignacio, jocxyen, jonatascm, karanctf, kebabsec, kyteg, m_Rassska, mektigboy, oyc_109, pedr02b2, rbserver, robee, rokinot, sach1r0, sashik_eth, simon135, slywaters
37.4667 USDC - $37.47
++i costs less gas compared to i++ or i += 1 for unsigned integer, as pre-increment is cheaper (about 5 gas per iteration). This statement is true even with the optimizer enabled.
Besides, In Solidity 0.8+, there’s a default overflow check on unsigned integers. It’s possible to uncheck this in for-loops and save some gas at each iteration, but at the cost of some code readability, as this uncheck cannot be made inline. The risk of overflow is inexistant for a uint256 here.
Original code: https://github.com/code-423n4/2022-07-fractional/blob/e2c5a962a94106f9495eb96769d7f60f7d5b14c9/src/Vault.sol#L104 https://github.com/code-423n4/2022-07-fractional/blob/e2c5a962a94106f9495eb96769d7f60f7d5b14c9/src/Vault.sol#L78
So the gas optimized code would be
for (uint256 i = 0; i < length;) { //... unchecked { ++i; } }