View and pure functions in Blockchain / Solidity - Mini Project: Build & Apply

View and Pure Functions in Solidity

📖 Scenario: You are creating a simple smart contract for a blockchain application. This contract stores a number and allows users to read it without changing the blockchain state. You will learn how to write view and pure functions, which do not modify the blockchain data.

🎯 Goal: Build a Solidity contract named NumberStore that stores a number and includes two functions: one view function to read the stored number, and one pure function to add two numbers without changing the contract state.

📋 What You'll Learn

Create a state variable called storedNumber of type uint.

Write a view function named getStoredNumber that returns the value of storedNumber.

Write a pure function named addNumbers that takes two uint parameters and returns their sum.

Deploy the contract and print the results of calling both functions.

💡 Why This Matters

🌍 Real World

View and pure functions are essential in blockchain smart contracts to read data efficiently and perform calculations without changing the blockchain state, saving gas fees.

💼 Career

Understanding these functions is crucial for blockchain developers to write optimized and secure smart contracts.

1

DATA SETUP: Create the contract and state variable

Create a Solidity contract named NumberStore and inside it declare a uint state variable called storedNumber initialized to 42.

Blockchain / Solidity

contract NumberStore {
    // Your code here
}

Need a hint?

Use contract NumberStore {} to start and declare uint storedNumber = 42; inside.

2

CONFIGURATION: Add a view function to read the stored number

Inside the NumberStore contract, write a view function named getStoredNumber that returns the storedNumber variable.

Blockchain / Solidity

contract NumberStore {
    uint storedNumber = 42;

    // Your code here
}

Need a hint?

Use function getStoredNumber() public view returns (uint) and return storedNumber.

3

CORE LOGIC: Add a pure function to add two numbers

Inside the NumberStore contract, write a pure function named addNumbers that takes two uint parameters called a and b, and returns their sum.

Blockchain / Solidity

contract NumberStore {
    uint storedNumber = 42;

    function getStoredNumber() public view returns (uint) {
        return storedNumber;
    }

    // Your code here
}

Need a hint?

Define function addNumbers(uint a, uint b) public pure returns (uint) and return a + b.

4

OUTPUT: Print the results of calling the functions

Write a simple test in Solidity that calls getStoredNumber and addNumbers with 5 and 7, then returns their results. Use public functions to expose these calls.

Blockchain / Solidity

contract NumberStore {
    uint storedNumber = 42;

    function getStoredNumber() public view returns (uint) {
        return storedNumber;
    }

    function addNumbers(uint a, uint b) public pure returns (uint) {
        return a + b;
    }

    // Your code here
}

Need a hint?

Create two public functions that call getStoredNumber() and addNumbers(5, 7) and return their results.