Why inheritance promotes code reuse in Blockchain / Solidity - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to inherit properties from the parent contract.

Blockchain / Solidity

contract Child is [1] {
    // Child contract code
}

Drag options to blanks, or click blank then click option'

AParent

BChild

CBase

DContract

Attempts:

3 left

💡 Hint

Common Mistakes

Using the child contract's own name instead of the parent.

Forgetting to specify the parent contract name.

The child contract inherits from the Parent contract to reuse its code.

2fill in blank

medium

Complete the code to call the parent constructor in the child contract.

Blockchain / Solidity

contract Child is Parent {
    constructor() [1] {
        Parent();
        // Initialization
    }
}

Drag options to blanks, or click blank then click option'

Ainternal

Bpublic

Cexternal

Doverride

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'override' keyword incorrectly.

Setting constructor visibility to external.

The child constructor must be public to call the parent's constructor properly.

3fill in blank

hard

Fix the error in overriding the parent function in the child contract.

Blockchain / Solidity

contract Child is Parent {
    function greet() [1] override returns (string memory) {
        return "Hello from Child!";
    }
}

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Avirtual

Boverride

Cpublic

Dexternal

Attempts:

3 left

💡 Hint

Common Mistakes

Placing 'override' as visibility.

Missing 'override' keyword after visibility.

The function visibility must be public to correctly override the parent's function.

4fill in blank

hard

Fill both blanks to define a function in the parent contract that can be overridden by the child.

Blockchain / Solidity

contract Parent {
    function greet() public [1] returns (string memory) {
        return "Hello from Parent!";
    }
}

contract Child is Parent {
    function greet() public [2] returns (string memory) {
        return "Hello from Child!";
    }
}

Drag options to blanks, or click blank then click option'

Avirtual

Boverride

Cexternal

Dinternal

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting 'virtual' in parent function.

Not using 'override' in child function.

The parent function must be marked virtual to allow overriding, and the child function must use override.

5fill in blank

hard

Fill all three blanks to create a reusable modifier in the parent and apply it in the child contract.

Blockchain / Solidity

contract Parent {
    modifier onlyOwner() [1] {
        require(msg.sender == owner, "Not owner");
        _;
    }
}

contract Child is Parent {
    function secureAction() [2] [3] onlyOwner {
        // secure code
    }
}

Drag options to blanks, or click blank then click option'

Apublic

Bvirtual

Coverride

Dinternal

Attempts:

3 left

💡 Hint

Common Mistakes

Making modifier public.

Missing 'override' keyword in child function.

Wrong function visibility.

The modifier is usually internal. The child function is public and uses override if it overrides a parent function.