Why Solidity is the language of Ethereum in Blockchain / Solidity - See It in Action

Why Solidity is the Language of Ethereum

📖 Scenario: You want to understand why Solidity is the main language used to write smart contracts on Ethereum blockchain. Smart contracts are like digital agreements that run automatically when conditions are met.

🎯 Goal: Build a simple Solidity smart contract that shows basic features of Solidity and understand why it fits Ethereum development.

📋 What You'll Learn

Create a simple Solidity contract with a state variable

Add a function to update the state variable

Add a function to read the state variable

Print the stored value after update

💡 Why This Matters

🌍 Real World

Smart contracts automate agreements like payments, voting, or ownership on Ethereum blockchain.

💼 Career

Understanding Solidity is essential for blockchain developers building decentralized applications (dApps) on Ethereum.

1

Create a Solidity contract with a state variable

Write a Solidity contract named SimpleStorage with a public uint variable called storedData initialized to 0. Use Solidity version pragma ^0.8.0.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract SimpleStorage {
    // Your code here
}

Hint

Start with the pragma line, then define the contract and the public variable.

2

Add a function to update the stored data

Inside the SimpleStorage contract, add a public function named set that takes a uint parameter called x and sets storedData to x.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract SimpleStorage {
    uint public storedData = 0;

    // Your code here
}

Hint

Define a public function named set that updates the storedData variable.

3

Add a function to read the stored data

Add a public view function named get that returns the current value of storedData as a uint.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract SimpleStorage {
    uint public storedData = 0;

    function set(uint x) public {
        storedData = x;
    }

    // Your code here
}

Hint

Create a public view function named get that returns storedData.

4

Test the contract by setting and getting the value

Write a comment showing how to call set(42) and then call get() to get the stored value 42.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract SimpleStorage {
    uint public storedData = 0;

    function set(uint x) public {
        storedData = x;
    }

    function get() public view returns (uint) {
        return storedData;
    }
}

// Your code here

Hint

Write comments showing how to use the set and get functions with the value 42.

Practice

1. Why is Solidity considered the main language for Ethereum smart contracts?

easy

A. Because it is a general-purpose programming language like Python

B. Because it is the oldest programming language available

C. Because it is used for building websites

D. Because it is specifically designed to work with Ethereum's blockchain

Solution

1. Step 1: Understand Solidity's purpose

   Solidity is created to write smart contracts that run on Ethereum's blockchain.

2. Step 2: Compare with other languages

   Unlike general-purpose languages, Solidity fits Ethereum's unique blockchain environment.

3. Final Answer:

   Because it is specifically designed to work with Ethereum's blockchain -> Option D

4. Quick Check:

   Solidity is Ethereum-specific = A [OK]

Hint: Solidity fits Ethereum blockchain needs specifically [OK]

Common Mistakes:

• Thinking Solidity is a general-purpose language
• Confusing Solidity with web development languages
• Assuming Solidity is the oldest language

2. Which of the following is the correct way to declare a state variable in Solidity?

easy

A. balance uint public;

B. int balance = 0

C. uint public balance;

D. var balance: uint;

Solution

1. Step 1: Recall Solidity variable syntax

   State variables are declared with type, visibility, and name, e.g., 'uint public balance;'.

2. Step 2: Check each option

   uint public balance; matches Solidity syntax; others have wrong order or missing semicolon.

3. Final Answer:

   uint public balance; -> Option C

4. Quick Check:

   Correct Solidity variable declaration = D [OK]

Hint: Remember: type visibility name; in Solidity [OK]

Common Mistakes:

• Omitting semicolon at the end
• Using wrong order of keywords
• Using 'var' which is not valid in Solidity

3. What will be the output of this Solidity function when called?

function getValue() public pure returns (uint) {
    uint a = 5;
    uint b = 10;
    return a + b;
}

medium

A. 15

B. 510

C. Error: missing return statement

D. 0

Solution

1. Step 1: Analyze the function logic

   The function adds two unsigned integers: 5 + 10.

2. Step 2: Calculate the sum

   5 + 10 equals 15, which is returned.

3. Final Answer:

   15 -> Option A

4. Quick Check:

   5 + 10 = 15 [OK]

Hint: Add numbers directly in return statement [OK]

Common Mistakes:

• Thinking numbers concatenate as strings
• Expecting a runtime error
• Missing return statement error

4. Identify the error in this Solidity code snippet:

contract Test {
    uint public count
    function increment() public {
        count += 1;
    }
}

medium

A. Missing semicolon after 'uint public count'

B. Function increment should be private

C. Variable count should be declared inside the function

D. No error, code is correct

Solution

1. Step 1: Check variable declaration syntax

   In Solidity, each statement must end with a semicolon; it's missing after 'uint public count'.

2. Step 2: Verify other parts

   Function visibility 'public' is correct; variable scope is appropriate.

3. Final Answer:

   Missing semicolon after 'uint public count' -> Option A

4. Quick Check:

   Semicolon missing = C [OK]

Hint: Every statement ends with a semicolon in Solidity [OK]

Common Mistakes:

• Ignoring missing semicolon errors
• Thinking function visibility must be private
• Declaring state variables inside functions

5. How does Solidity's design help automate agreements on Ethereum compared to traditional programming languages?

hard

A. It runs faster than all other programming languages

B. It includes built-in features for blockchain transactions and contract state management

C. It uses simple English-like syntax for all programming tasks

D. It requires no gas fees to execute contracts

Solution

1. Step 1: Understand Solidity's blockchain focus

   Solidity has special features to handle blockchain transactions and manage contract states automatically.

2. Step 2: Compare with other languages

   Traditional languages lack these blockchain-specific tools, making Solidity better for smart contracts.

3. Final Answer:

   It includes built-in features for blockchain transactions and contract state management -> Option B

4. Quick Check:

   Blockchain features in Solidity = B [OK]

Hint: Solidity has blockchain tools built-in [OK]

Common Mistakes:

• Assuming Solidity is the fastest language
• Believing Solidity uses English-like syntax for all tasks
• Thinking Solidity contracts execute without gas fees