🤝Gas Saving Technique 28: && operator uses more gas

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Introduction: In the Solidity smart contract realm, efficient gas usage is paramount. One might think that condensing multiple conditions within a single require statement using the && operator is efficient, but in practice, this can consume more gas than splitting the conditions into separate require statements. This tutorial will delve into the reasons behind this, demonstrating the gas-saving potential of splitting conditions.

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Concept: The require function in Solidity is used to ensure that certain conditions are met before executing subsequent code. When combining multiple conditions with the && operator within a single require, Solidity evaluates all conditions even if the first one fails. On the contrary, by separating the conditions into distinct require statements, Solidity can fail fast on the first condition not met, potentially saving gas.

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Underlying Problem:

1. Sequential Evaluation: The && operator results in a sequential evaluation of conditions. If the first condition is false, subsequent conditions are still evaluated, leading to unnecessary gas consumption.

2. Fail Fast Principle: Combining conditions prevents utilizing the "fail fast" principle, which can be more gas-efficient when conditions are split.

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Example:

Using && Operator in a Single require:

solidityCopy coderequire(amount_ != uint256(0) && amount_ <= MAX_TOTAL_XDEFI_SUPPLY, "INVALID_AMOUNT");

Splitting the Conditions into Separate require Statements:

solidityCopy coderequire(amount_ != uint256(0), "INVALID_AMOUNT_ZERO");
require(amount_ <= MAX_TOTAL_XDEFI_SUPPLY, "INVALID_AMOUNT_OVERLIMIT");

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Recommendation:

1. Scrutinize your contracts and locate any require statements using the && operator to combine multiple conditions.

2. Decompose these combined conditions into individual require statements.

3. Ensure that the ordering of conditions remains logical and doesn't compromise the contract's security.

4. Test the refactored code thoroughly to ensure consistent behavior and actual gas savings.

5. When writing new contracts, consider adopting the "fail fast" principle by default.

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Conclusion: In the world of smart contracts where every gas unit matters, seemingly minor changes can lead to significant gas savings. By splitting conditions in require statements instead of chaining them with the && operator, developers can optimize their contracts for efficiency. Remember: In the blockchain space, efficiency is not just about code performance, but also about the cost-effectiveness of executing that code.