Gas optimization for smart contracts: 2. Fixed-length arrays

Jul 25, 2023#Web3 #Blockchain #NFT #DeFi #DAO #DApp #区块链 #區塊鏈 #加密货币 #DeGame #链游 #Crypto #比特币 #以太坊 #Ethereum #合约开发260

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In smart contract development, using fixed-length arrays can effectively reduce gas costs compared to dynamic arrays. Dynamic arrays require copying and shifting operations, which increase gas consumption. On the other hand, fixed-length arrays have a fixed length and can be assigned directly through indexing, without the need for shifting. Therefore, when the length is known or the upper limit can be estimated, using fixed-length arrays can reduce gas consumption. However, it is important to note that fixed-length arrays cannot be extended, so dynamic arrays should still be used if expansion is expected. Using fixed-length arrays in smart contract optimization can significantly reduce gas costs, but it is necessary to consider whether the business scenario truly requires a fixed length. By flexibly utilizing the advantages and disadvantages of dynamic and fixed-length arrays, the optimal gas usage can be achieved.

In smart contract development, dynamic arrays often consume more gas, while using fixed-length arrays can effectively reduce gas costs.

Assigning values to dynamic arrays requires copying, and deleting elements requires shifting, both of which increase gas consumption. For example:

uint[] public arr;

function f() public {
  for(uint i = 0; i < 100; i++) {
    arr.push(i); 
  }
}

In contrast, fixed-length arrays have a fixed length, and values can be assigned directly through indexing without the need for shifting after deletion. For example:

uint[100] public arr;

function f() public {
  for(uint i = 0; i < 100; i++) {
    arr[i] = i;
  }
}

Therefore, in cases where the length is known or the upper limit can be estimated, using fixed-length arrays can reduce gas consumption. It should be noted that fixed-length arrays cannot be extended in length, so if expansion is expected, dynamic arrays should still be used.

Using fixed-length arrays in smart contract optimization can significantly reduce gas costs, but it is necessary to consider whether the business scenario really requires a fixed length. Flexibly utilizing the advantages and disadvantages of dynamic arrays and fixed-length arrays can achieve the optimal gas usage efficiency.