Ethereum Developer Solidity Smart Contract Development 3

Question 1

In Solidity, what does `msg.sender` refer to?

Accepted Answer

The address that called the current function

Answer

`msg.sender` is a global variable representing the address of the entity that directly called the current function.

Question 2

What is the purpose of the `SafeMath` library in older Solidity contracts?

Accepted Answer

To prevent integer overflow and underflow vulnerabilities

Answer

`SafeMath` adds checked arithmetic operations that revert on overflow/underflow, a risk that was automatic only from Solidity 0.8.0 onward.

Question 3

What does the `abstract` keyword indicate about a Solidity contract?

Accepted Answer

It has at least one unimplemented function and cannot be deployed directly

Answer

An `abstract` contract contains at least one function without implementation and must be inherited and completed before deployment.

Question 4

How does Solidity handle integer division by default?

Accepted Answer

It truncates toward zero with no remainder

Answer

Solidity integer division truncates the result toward zero, discarding any fractional part.

Question 5

What is the maximum number of indexed parameters allowed in a Solidity event?

Accepted Answer

3

Answer

Solidity allows up to 3 indexed event parameters, which are stored as topics in the transaction log for efficient filtering.

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