Reference types behavior in Blockchain / Solidity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a reference type variable in Solidity.

Blockchain / Solidity

string memory [1] = "hello";

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Agreeting

Baddress

Cbool

Duint

Attempts:

3 left

💡 Hint

Common Mistakes

Using a type name instead of a variable name.

Using a value instead of a variable name.

In Solidity, string memory declares a reference type variable named greeting.

2fill in blank

medium

Complete the code to assign a reference type variable to another in Solidity.

Blockchain / Solidity

string memory name1 = "Alice";
string memory [1] = name1;

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Aname2

Bbool

Caddress

Duint

Attempts:

3 left

💡 Hint

Common Mistakes

Using a type name instead of a variable name.

Using the same variable name twice.

Assigning name1 to name2 copies the reference type string in memory.

3fill in blank

hard

Fix the error in the function parameter declaration for a reference type in Solidity.

Blockchain / Solidity

function setName(string [1] newName) public {
    name = newName;
}

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Aaddress

Buint

Cstorage

Dmemory

Attempts:

3 left

💡 Hint

Common Mistakes

Using storage instead of memory for function parameters.

Omitting the data location keyword.

Function parameters of reference types must be declared with memory to indicate temporary data.

4fill in blank

hard

Fill both blanks to correctly declare and assign a dynamic array reference type in Solidity.

Blockchain / Solidity

uint[] [1];
[2] = new uint[](5);

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Anumbers

Caddress

Dbool

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for declaration and assignment.

Using invalid types for the array variable.

The variable numbers is declared as a dynamic array and then initialized with length 5.

5fill in blank

hard

Fill all three blanks to create a mapping from address to a dynamic array of uint in Solidity.

Blockchain / Solidity

mapping([1] => [2]) public [3];

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Aaddress

Buint[]

Cbalances

Dstring

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect types for mapping keys or values.

Using an invalid variable name for the mapping.

This mapping links each address to a dynamic array of uint called balances.