CBDE 試験問題を無料オンラインアクセス

Checking the balance of an address inside a loop of a smart contract constantly:

• A.cost gas every time we check the balance.
• B.doesn't cost any gas.

EVM assembly:

• A.is another language similar to LLL, more secure than Solidity.
• B.is much better than Solidity and a viable alternative.
• C.can be split across multiple files, but every contract must be in a file with the same name as the contract itself.

It's possible to access the blockchain via an Ethereum Node:

• A.by any programming language, as long as it adheres to the JSON-RPC standard.
• B.only via JavaScript because there is the proprietary Web3.js library.

A Struct is a great way:

• A.to implement pointers to other contracts that can hold new datatypes.
• B.to hold instances of other contracts.
• C.to define a new datatype in Solidity, so you don't need to use objects of another contract.

When solidity is compiled then also Metadata is generated:

• A.the ABI array and the Metadata are not generated when solidity is compiled to bytecode, its generated by a migration software which deploys the smart contract on the blockchain.
• B.the Metadata contains the ABI Array, which defines the Interface to interact with the Smart Contract. Metadata can also contain the address of the smart contract when it gets deployed.
• C.metadata contains the address, and the size of the smart contract. The ABI Array is generated externally upon deploying the smart contract.