SimpleStorage — Foundry Project

A beginner-friendly Solidity project built with :contentReference[oaicite:0]{index=0}.

This project demonstrates:

• Solidity basic data types
• State variables
• Structs
• Arrays
• Mappings
• Memory vs Storage vs Calldata
• Reading & writing blockchain state
• Deploying contracts with Foundry scripts

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Project Structure

.
├── src/
│   └── SimpleStorage.sol
│
├── script/
│   └── DeploySimpleStorage.sol
│
├── test/
│
├── foundry.toml
└── README.md

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Smart Contract

SimpleStorage.sol

A simple contract that stores and retrieves a favorite number while showcasing common Solidity concepts.

Features

• Store and update a number
• Retrieve stored value
• Add people with favorite numbers
• Map names to favorite numbers
• Demonstrates:
  • bool
  • uint
  • int
  • string
  • address
  • bytes32
  • arrays
  • structs
  • mappings

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Functions

Store a Number

function store(uint256 _favNum) public

Updates the stored favorite number.

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Retrieve Stored Number

function retrieve() public view returns (uint256)

Returns the current favorite number.

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Add a Person

function addPerson(string memory _name, uint256 _favNum) public

Adds a person and maps their name to a favorite number.

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Deployment Script

DeploySimpleStorage.sol

Deploys the SimpleStorage contract using Foundry scripting.

Uses:

• vm.startBroadcast()
• vm.stopBroadcast()

to send deployment transactions.

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Getting Started

Clone the Repository

git clone <REPOSITORY_URL>

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Navigate to the Project Directory

cd <PROJECT_DIRECTORY>

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Install Foundry

If Foundry is not installed:

Follow the up to date installation through this link

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Install Forge

Inside the project directory, install the dependencies:

forge install

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Build

Compile the smart contracts.

forge build

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Test

Test files are not included yet.

A dedicated test suite using Forge will be added in future updates.

Example command once tests are implemented:

forge test

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Format

Format Solidity files.

forge fmt

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Start Local Node

Run a local Ethereum development node using Anvil.

anvil

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Secure Local Deployment

1. Create an Encrypted Keystore

cast wallet import local-deployer --interactive

You will:

• paste your private key once
• create a secure password

The key will be encrypted and stored locally.

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2. Deploy the Contract

forge script script/DeploySimpleStorage.sol:DeploySimpleStorage \
--rpc-url http://localhost:8545 \
--account local-deployer \
--broadcast

Foundry will securely prompt for your password.

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After Deployment (Interact with Contract)

Once the contract is deployed, you can interact with it using cast.

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1. Save Your Contract Address

After deployment, copy the deployed contract address

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2. Set a New Favorite Number (Transaction)

This sends a transaction to update the state.

cast send <CONTRACT_ADDRESS> \
"store(uint256)" 42 \
--rpc-url http://localhost:8545 \
--account local-deployer

• store(uint256) → function being called
• 42 → new favorite number
• --account local-deployer → your saved wallet

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3. Read the Stored Value (No Transaction)

This is a read-only call (no gas spent).

cast call <CONTRACT_ADDRESS> \
"retrieve()(uint256)" \
--rpc-url http://localhost:8545

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4. Optional: Check Account Balance

cast balance <YOUR_ADDRESS> --rpc-url http://localhost:8545

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5. Verify Transaction Details (Optional)

You can inspect a transaction hash:

cast tx <TX_HASH> --rpc-url http://localhost:8545

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Summary

• cast send → writes to blockchain (state change)
• cast call → reads from blockchain (no gas)
• --account [NAME] → uses your secure wallet

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Helpful Commands

Convert HEX to Decimal

cast --to-base 0xfd31c dec

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Concepts Covered

Data Locations

Storage

Permanent blockchain data.

Memory

Temporary and modifiable during execution.

Calldata

Temporary, read-only function input data.

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Tools Used

Foundry, which includes:

• Forge → testing framework
• Cast → blockchain interaction CLI
• Anvil → local Ethereum node
• Chisel → Solidity REPL

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Documentation

• Foundry Book
• Solidity Docs

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License

MIT