What costs gas in the EVM?

Gas

When creating the contracts for trading tokens or flipping NFT's, one has to consider the actual gas implications of their functions. Having clean, efficient code that runs in a bot-dominated niche dramatically helps with volume. Here are some pointers to pay attention to.

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What doesn't cost gas:

• reading state variables (local)
• reading the contract balance via <address>.balance or this.balance
• reading public block variables
• calling a pure function
• read opcodes in inline assembly

What does cost gas:

• sending Ethereum (ethers)
• creating contracts
• changing state variables
• emitting Events
• executing any non-pure or non-view function
• selfdestruct (deleting a contract and sending all stored ether to another contract)
• low-level EVM calls
• write opcodes in inline assembly