The Complete Solidity Course - Zero to Advanced for Blockchain and Smart Contracts - Solution - Modifier Function

The video tutorial guides viewers through creating and implementing a 'modifier' in code, specifically focusing on the 'only by' modifier. It explains how to set up the modifier to restrict access based on the message sender's address, ensuring only authorized users can execute certain functions. The tutorial includes testing the modifier with different accounts, handling errors, and understanding why certain errors occur. The video concludes with a brief introduction to the next topic, 'only after', encouraging viewers to take a break before continuing.

What is the primary purpose of the 'only by' modifier discussed in the video?

• To allow any user to access a function

• To restrict function access to a specific address

• To modify the input parameters of a function

• To enhance the performance of a function

What happens if the condition in the 'only by' modifier fails?

• The input is modified

• The function is skipped

• The function executes normally

• An error message is displayed

How can the 'only by' modifier be used to restrict access to a function?

• By adding it to the function without any parameters

• By specifying the address of the authorized user

• By removing all input checks

• By using it as a standalone function

What is the result of attempting to change the owner from an unauthorized account?

• The function executes with a warning

• The function is ignored

• The owner is changed successfully

• An error indicating 'Sender not authorized' is shown

Why is it important to test the modifier with different accounts?

• To improve the speed of the function

• To ensure the modifier is ignored

• To verify that the access control works as intended

• To allow any account to change the owner