Constants and immutables in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a constant value for the token name.

Blockchain / Solidity

contract Token {
    string public constant [1] = "MyToken";
}

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ATOKEN_NAME

BtokenName

Ctoken_name

DTokenName

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or camelCase names for constants.

Constants in blockchain smart contracts are usually named in uppercase letters with underscores.

2fill in blank

medium

Complete the code to declare an immutable variable for the contract owner address.

Blockchain / Solidity

contract Ownership {
    address public immutable [1];

    constructor(address _owner) {
        [1] = _owner;
    }
}

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AOWNER_ADDRESS

BownerAddress

Cowner

DOwner

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase names for immutable variables.

Trying to assign immutable variables outside the constructor.

Immutable variables are usually named in camelCase and set once during contract deployment.

3fill in blank

hard

Fix the error in the code by choosing the correct keyword to declare a constant.

Blockchain / Solidity

contract Example {
    uint256 public [1] VALUE = 1000;
}

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Alet

Bimmutable

Cconstant

Dvar

Attempts:

3 left

💡 Hint

Common Mistakes

Using immutable instead of constant for fixed values.

Using JavaScript keywords like var or let.

The keyword constant is used to declare compile-time constants in smart contracts.

4fill in blank

hard

Fill both blanks to declare an immutable uint variable and assign it in the constructor.

Blockchain / Solidity

contract Config {
    uint256 public [1] [2];

    constructor(uint256 _value) {
        [2] = _value;
    }
}

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Aimmutable

Bconstant

CconfigValue

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names in declaration and assignment.

Forgetting to add the immutable keyword.

The variable name must be the same in declaration and assignment. The keyword immutable is missing and should be added before the variable name.

5fill in blank

hard

Fill all three blanks to declare a constant string, an immutable address, and assign the immutable in the constructor.

Blockchain / Solidity

contract Demo {
    string public constant [1] = "DemoToken";
    address public immutable [2];

    constructor(address _admin) {
        [3] = _admin;
    }
}

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ACONSTANT_NAME

Badmin

CADMIN_ADDRESS

DTOKEN_NAME

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up constant and immutable naming conventions.

Assigning to a different variable name in the constructor.

The constant string is named TOKEN_NAME. The immutable address variable is admin, which is assigned in the constructor.