Why Solidity is the language of Ethereum in Blockchain / Solidity - Visual Breakdown

Concept Flow - Why Solidity is the language of Ethereum

Ethereum Blockchain

↓

Need for Smart Contracts

↓

Choose a Language

↓

Solidity Created

↓

Write Smart Contracts

↓

Deploy on Ethereum

↓

Execute on Ethereum Virtual Machine (EVM)

This flow shows how Ethereum needed a language for smart contracts, leading to Solidity's creation, which lets developers write and deploy contracts on Ethereum.

Execution Sample

Blockchain / Solidity

pragma solidity ^0.8.0;

contract SimpleStorage {
    uint storedData;
    function set(uint x) public {
        storedData = x;
    }
    function get() public view returns (uint) {
        return storedData;
    }
}

A simple Solidity contract that stores and retrieves a number on Ethereum.

Execution Table

Step	Action	Variable/State	Result/Effect
1	Deploy contract SimpleStorage	storedData	initialized to 0 on blockchain
2	Call set(42)	storedData	updated to 42 on blockchain
3	Call get()	storedData	returns 42
4	Call set(100)	storedData	updated to 100 on blockchain
5	Call get()	storedData	returns 100
6	No more calls	-	Contract state remains storedData=100

💡 Execution stops when no more contract calls are made.

Variable Tracker

Variable	Start	After set(42)	After set(100)	Final
storedData	0	42	100	100

Key Moments - 3 Insights

Why does storedData keep its value between function calls?

Because storedData is stored on the blockchain inside the contract's state, it persists across calls as shown in execution_table steps 2, 4, and 6.

Why do we need Solidity instead of just using regular programming languages?

Solidity is designed to work with Ethereum's blockchain and its virtual machine (EVM), enabling secure, decentralized contract execution, unlike regular languages that don't interact with blockchain.

What happens when we deploy the contract?

Deploying uploads the contract code to Ethereum, initializing its state (storedData=0), making it ready to accept calls, as shown in execution_table step 1.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of storedData after step 2?

A 42

B 0

C 100

D Undefined

💡 Hint

Check the 'Variable/State' column at step 2 in the execution_table.

At which step does storedData change to 100?

A Step 3

B Step 5

C Step 4

D Step 6

💡 Hint

Look at the 'Action' and 'Variable/State' columns in execution_table rows.

If we never call set(), what would get() return according to variable_tracker?

A 42

B 0

C 100

D Error

💡 Hint

Check the 'Start' value of storedData in variable_tracker.

Concept Snapshot

Solidity is Ethereum's main language for smart contracts.
It compiles to bytecode for the Ethereum Virtual Machine (EVM).
Contracts store data on blockchain, persisting between calls.
Solidity syntax is similar to JavaScript and C++.
It enables decentralized, secure contract execution on Ethereum.

Full Transcript

Ethereum needed a way to write smart contracts that run on its blockchain. Solidity was created as a language designed specifically for this purpose. When a Solidity contract is deployed, it is stored on the Ethereum blockchain with an initial state. Functions like set() can change the contract's stored data, which persists between calls because it is saved on the blockchain. The get() function reads this stored data. Solidity compiles to code that runs on the Ethereum Virtual Machine, enabling decentralized and secure contract execution. This visual trace showed deploying a simple contract, updating stored data, and retrieving it, illustrating why Solidity is the language of Ethereum.

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