Staking mechanisms in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a staking balance mapping in Solidity.

Blockchain / Solidity

mapping(address => uint256) public [1];

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AstakeAmount

BstakingBalance

Cbalances

DuserStake

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name that does not clearly represent staking balances.

Forgetting to specify the mapping key or value types.

The stakingBalance mapping is commonly used to track how much each address has staked.

2fill in blank

medium

Complete the code to allow users to stake tokens by updating their balance.

Blockchain / Solidity

function stakeTokens(uint256 _amount) public {
    require(_amount > 0, "Amount must be greater than zero");
    [1][msg.sender] += _amount;
}

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AstakingBalance

Bbalances

CuserStake

DstakeAmount

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong mapping name.

Not using msg.sender as the key.

The stakingBalance mapping is updated to add the staked amount for the sender.

3fill in blank

hard

Fix the error in the function that allows users to unstake their tokens.

Blockchain / Solidity

function unstakeTokens() public {
    uint256 balance = [1][msg.sender];
    require(balance > 0, "No tokens to unstake");
    stakingBalance[msg.sender] = 0;
    // Transfer tokens back to user
}

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AstakingBalance

BuserStake

Cbalances

DstakeAmount

Attempts:

3 left

💡 Hint

Common Mistakes

Using a mapping name that does not exist or is inconsistent.

Not checking the correct balance before unstaking.

The correct mapping to check the user's staked tokens is stakingBalance.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps user addresses to their staked amounts greater than zero.

Blockchain / Solidity

activeStakes = {address: amount for (address, amount) in [1].items() if amount [2] 0};

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AstakingBalance

B>

C==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong comparison operator.

Using a mapping name that does not exist.

This comprehension filters stakingBalance to include only users with amounts greater than zero.

5fill in blank

hard

Fill all three blanks to calculate rewards for each user with staked tokens above a threshold.

Blockchain / Solidity

rewards = { [1]: [2] * rewardRate for ([3], amount) in stakingBalance.items() if amount > threshold };

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Auser

Bamount

Dstake

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up variable names in the comprehension.

Using incorrect variable names for keys or values.

The comprehension uses user as the key, multiplies amount by rewardRate, and iterates over stakingBalance items with user and amount.