If-else statements in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the transaction amount is greater than 1000.

Blockchain / Solidity

if (transaction.amount [1] 1000) {
    approveTransaction();
} else {
    rejectTransaction();
}

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

A>

B!=

C==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' will check the wrong condition.

Using '==' checks equality, not greater than.

The code checks if the transaction amount is greater than 1000 using the > operator.

2fill in blank

medium

Complete the code to set the status to 'approved' if the balance is sufficient.

Blockchain / Solidity

if (user.balance [1] transaction.amount) {
    status = 'approved';
} else {
    status = 'denied';
}

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

A>=

B==

C<

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' will approve when balance is less, which is wrong.

Using '==' only approves if balance is exactly equal.

The code checks if the user's balance is greater than or equal to the transaction amount to approve it.

3fill in blank

hard

Fix the error in the if-else condition to check if the sender is the owner.

Blockchain / Solidity

if (sender [1] owner) {
    execute();
} else {
    revert();
}

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

A=

B==

C===

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' causes assignment, not comparison.

Using '===' is invalid syntax in blockchain smart contract languages.

In blockchain smart contracts, '==' is used to check equality between sender and owner.

4fill in blank

hard

Fill both blanks to approve if the amount is less than 500 and the sender is verified.

Blockchain / Solidity

if (transaction.amount [1] 500 && sender.verified [2] true) {
    approve();
} else {
    deny();
}

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

A<

B==

C!=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' instead of '<' reverses the amount check.

Using '!=' for verification checks the wrong condition.

The code approves if the amount is less than 500 and the sender is verified (true).

5fill in blank

hard

Fill all three blanks to reject if the balance is less than amount or sender is not verified.

Blockchain / Solidity

if (user.balance [1] transaction.amount || sender.verified [2] [3]) {
    reject();
} else {
    accept();
}

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

A<

B==

Cfalse

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' instead of '==' reverses the verification logic.

Using 'true' instead of 'false' checks the wrong condition.

The code rejects if balance is less than amount or sender is not verified (verified == false).