Foundry DeFi Stablecoin CodeHawks Audit Contest
Cyfrin
DeFiFoundry
15,000 USDC
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Submission Details
Severity: gas
Valid

Improvement in the for loops to save gas.

pratred

Summary

Use this methods to save gas while using for loops.

  1. No need to explicitly initialize variables with default values (eg : uint256 i=0).

  2. The increment in the for loop’s post condition can be made unchecked.

  3. Caching the length in for loops.

Vulnerability Details

  1. Instead of this loop at https://github.com/Cyfrin/2023-07-foundry-defi-stablecoin/blob/d1c5501aa79320ca0aeaa73f47f0dbc88c7b77e2/src/DSCEngine.sol#L118C9-L121C10

for (uint256 i = 0; i < tokenAddresses.length; i++) {
s_priceFeeds[tokenAddresses[i]] = priceFeedAddresses[i];
s_collateralTokens.push(tokenAddresses[i]);
}

Use this for loop

for (uint256 i ; i < tokenAddresses.length; ) {
s_priceFeeds[tokenAddresses[i]] = priceFeedAddresses[i];
s_collateralTokens.push(tokenAddresses[i]);
unchecked{
i++;
}
}

  1. Instead of this loop at https://github.com/Cyfrin/2023-07-foundry-defi-stablecoin/blob/d1c5501aa79320ca0aeaa73f47f0dbc88c7b77e2/src/DSCEngine.sol#L353C8-L357C10

for (uint256 i = 0; i < s_collateralTokens.length; i++) {
address token = s_collateralTokens[i];
uint256 amount = s_collateralDeposited[user][token];
totalCollateralValueInUsd += getUsdValue(token, amount);
}

Use this for loop

uint256 _s_collateralTokens = s_collateralTokens.length;
for (uint256 i; i < _s_collateralTokens;) {
address token = s_collateralTokens[i];
uint256 amount = s_collateralDeposited[user][token];
totalCollateralValueInUsd += getUsdValue(token, amount);
unchecked{
i++;
}
}

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