Event declaration in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an event named Transfer.

Blockchain / Solidity

event [1](address indexed from, address indexed to, uint256 value);

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ATransfer

BEvent

CLog

DNotify

Attempts:

3 left

💡 Hint

Common Mistakes

Using a keyword like 'Event' instead of the event name.

Using a generic word like 'Log' or 'Notify' which are not event names.

The keyword Transfer is the name of the event being declared.

2fill in blank

medium

Complete the code to declare an event named Approval with three parameters.

Blockchain / Solidity

event Approval(address indexed owner, address indexed [1], uint256 value);

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Areceiver

Bspender

Csender

Dcaller

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'receiver' or 'sender' which are not standard names here.

Confusing the parameter with the owner address.

The second parameter in the Approval event is usually called spender.

3fill in blank

hard

Fix the error in the event declaration by completing the missing keyword.

Blockchain / Solidity

event Deposit(address indexed from, uint256 amount) [1];

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Aemit

Bpublic

Cexternal

Danonymous

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'emit' which is for calling events, not declaring them.

Using visibility keywords like 'public' or 'external' which are invalid here.

The anonymous keyword marks the event as anonymous, which is valid in event declarations.

4fill in blank

hard

Fill both blanks to declare an event named OwnershipTransferred with two indexed address parameters.

Blockchain / Solidity

event OwnershipTransferred(address indexed [1], address indexed [2]);

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ApreviousOwner

BnewOwner

Cowner

Dadmin

Attempts:

3 left

💡 Hint

Common Mistakes

Using generic names like 'owner' or 'admin' instead of descriptive ones.

Mixing the order of parameters.

The event parameters are named previousOwner and newOwner to indicate ownership change.

5fill in blank

hard

Fill all three blanks to declare an event named TokenMinted with an indexed address minter, a tokenId, and a value.

Blockchain / Solidity

event TokenMinted(address indexed [1], uint256 [2], uint256 [3]);

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Aminter

BtokenId

Camount

Downer

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'owner' instead of 'minter' for the first parameter.

Confusing 'tokenId' with 'amount'.

The event parameters are minter (indexed address), tokenId, and amount.