Claude Code Complete Tutorial 2026

Why Claude Code Stands Out

Most AI coding tools (Cursor, GitHub Copilot) exist as IDE plugins, but Claude Code runs in the terminal—a design choice with deep implications:

More complete context: Can read the entire codebase, not just the current file

Freer tool invocation: Can run shell commands, git operations, file system operations

Suitable for complex tasks: Cross-file refactoring, debugging production bugs, understanding large codebases

One-sentence positioning: Claude Code = a senior engineer who truly understands your entire project

Installation and Configuration

Prerequisites

Node.js 18+

A valid Anthropic API Key (Apply here)

Installation Steps

bash
Global install
npm install -g @anthropic-ai/claude-code
Or run directly with npx (no install needed)
npx @anthropic-ai/claude-code

Configure API Key

bash
export ANTHROPIC_API_KEY=sk-ant-xxxxx
Permanent configuration (add to ~/.zshrc or ~/.bashrc)
echo 'export ANTHROPIC_API_KEY=sk-ant-xxxxx' >> ~/.zshrc

Core Workflows

1. Launch and Basic Conversation

bash
Start in the project root
cd /your/project
claude

Claude Code automatically scans the project structure and understands the codebase. On first launch, it will ask whether to allow tool permissions (file read/write, shell execution).

2. Code Review

Real-world use case: Run a review with Claude Code before submitting a PR

Please review the code changes from the last 3 commits, focusing on:
Potential bugs and edge cases
Performance issues
Consistency with existing code style
Missing test cases

Claude Code will automatically execute git diff HEAD~3, read the relevant files, and provide specific improvement suggestions.

3. Multi-file Refactoring

This is where Claude Code shines—systematic refactoring across files:

I need to migrate all class components in the project to React Hooks.
First list all class component files, then migrate them one by one,
ensuring functionality remains unchanged and updating related test files.

Claude Code will first run grep -r "extends Component" src/ to find all target files, then complete the migration file by file.

4. Debugging Production Bugs

Production error:
TypeError: Cannot read property 'userId' of undefined
  at UserService.getProfile (src/services/user.ts:142)
Please find the root cause and fix it, while adding defensive code to prevent similar issues.

5. Automatic Test Generation

Generate complete unit tests for the calculateDiscount function in src/utils/payment.ts,
covering: normal discount calculation, edge cases (0% discount, 100% discount), error handling for invalid inputs.
Use Jest + TypeScript.

Advanced Tips

Custom Project Context (CLAUDE.md)

Create a CLAUDE.md file in the project root; Claude Code reads it on every launch:

markdown
Project Description
Tech Stack
Next.js 14 + TypeScript
Prisma + PostgreSQL
Testing: Jest + React Testing Library
Code Conventions
Use functional components
State management with Zustand
API routes in src/app/api/
Common Commands
Dev: bun dev
Test: bun test

With this file, you don't need to repeat the project background every conversation.

Slash Commands

CommandPurpose

/helpView all available commands /clearClear conversation history (save tokens) /compactCompress conversation history /costView token consumption for this conversation /exitExit Claude Code

Claude Code vs Cursor: How to Choose?

DimensionClaude CodeCursor

InterfaceTerminalGUI IDE Context Window200k tokensLimited Best ForComplex refactoring, large projectsDaily coding, completions Learning CurveSteeperGentler PricingPay per API usage$20/month

Recommendation: They are not mutually exclusive. Use Cursor for daily coding, Claude Code for large refactoring/code reviews.

Cost Control Tips

Use /compact wisely: Compress history when conversations get long to reduce repeated tokens

Be precise in prompts: Avoid vague "help me optimize code"; state specific requirements

CLAUDE.md replaces repeated explanations: Write it once, auto-loaded every time

Choose the right model: Use Claude Haiku for simple tasks, Opus for complex ones

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Further Reading

MCP Server Complete Guide

Windsurf vs Cursor vs Claude Code Ultimate Comparison

AI Coding Tools Roundup 2026