Claude Code Complete Tutorial

From installation to mastery — A comprehensive guide to Claude Code covering setup, core features, model selection, practical examples and best practices

Claude Code Complete Tutorial¶

This is a comprehensive Claude Code tutorial designed for developers. Whether you're new to AI coding tools or migrating from other tools, this guide will help you master Claude Code — the most powerful AI coding assistant in 2026.

1. What is Claude Code¶

An Agentic Coding Assistant, Not Code Completion¶

Claude Code is Anthropic's official CLI agentic coding assistant. Unlike traditional code completion tools (like GitHub Copilot), Claude Code works like an experienced developer:

• Autonomous planning: Describe your task, it creates an execution plan
• Direct code operations: Read, edit, and create any file in your project
• Terminal execution: Run tests, install dependencies, execute builds
• Deep project understanding: 200K token context window (Opus 4.6 supports up to 1M)
• Sub-agent delegation: Break complex tasks into parallel sub-agents

2025-2026 Key Updates¶

Why Use QCode.cc¶

Through QCode.cc you get:

• Asia-Pacific low-latency nodes, no VPN needed
• Up to 80% cost savings compared to official pricing
• Claude Code & Codex share plan quota — one plan, two tools
• High availability across multiple nodes

2. Installation & Setup¶

System Requirements¶

Install¶

npm install -g @anthropic-ai/claude-code

Configure QCode.cc¶

# Add to ~/.bashrc or ~/.zshrc
export ANTHROPIC_BASE_URL=https://asia.qcode.cc/api
export ANTHROPIC_API_KEY=cr_your_api_key

Verify¶

claude --version
claude -p "Hello, introduce yourself"

3. First Use¶

Start Claude Code¶

cd ~/my-project
claude

Permission Modes¶

Your First Task¶

> Analyze this project's architecture and explain the main modules

Claude will automatically read package.json, browse source files, and provide a structured analysis.

4. Core Features¶

Plan Mode¶

> /plan
> I want to add user authentication using JWT

Claude will analyze, propose a plan, then execute after your approval.

Extended Thinking¶

Opus 4.6 performs deep internal reasoning for complex problems:

> This concurrency bug has been investigated for two days. Analyze the race condition in src/worker.ts

Sub-agents¶

> Review this PR and check for security vulnerabilities simultaneously

Claude spawns parallel sub-agents for independent tasks.

Key Commands¶

Context Management¶

/cost      # Check usage
/compact   # Compress (keeps key info)
/clear     # Fresh session

Best practice: /compact when context > 70%, /clear between different tasks.

5. CLAUDE.md — Project Configuration¶

Create with /init, or manually:

# MyApp

## Tech Stack

- React 19 + TypeScript + Vite + Tailwind CSS

## Commands

- Dev: `pnpm dev`
- Test: `pnpm test`
- Build: `pnpm build`

## Coding Standards

- Functional components only, no class components
- No `any` types
- Commit format: feat: / fix: / docs:

Full guide: CLAUDE.md Configuration Guide

6. Model Selection¶

/model opus    # Switch to Opus
/model sonnet  # Switch to Sonnet
/model haiku   # Switch to Haiku

Recommended strategy: Sonnet 70% (daily work) + Opus 15% (key decisions) + Haiku 15% (simple tasks).

7. Advanced Tips¶

Hooks¶

Auto-format after file changes:

{
  "hooks": {
    "PostToolUse": [{
      "matcher": "Write|Edit",
      "hooks": [{ "type": "command", "command": "npx prettier --write $FILEPATH" }]
    }]
  }
}

MCP Servers¶

Connect external tools:

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"],
      "env": { "GITHUB_TOKEN": "ghp_xxx" }
    }
  }
}

Full guides: Hooks System | MCP Servers

8. Practical Examples¶

Example 1: Understand a New Codebase¶

> Analyze this project: tech stack, core modules, data flow, and draw an ASCII architecture diagram

Example 2: Feature Implementation with Plan Mode¶

> /plan
> Add rate limiting: 60 requests/min per user, Redis-backed, 429 with Retry-After header

Example 3: Complex Bug Debugging¶

/model opus
> Users report inventory going negative under concurrent orders. Analyze the race condition.

Example 4: Batch Refactoring¶

> Refactor all class components in src/components/ to functional components with Hooks

Example 5: CI/CD Integration¶

claude -p "Review this PR for security and performance issues" \
  --output-format json --max-turns 3 --allowedTools Read,Glob,Grep

9. Claude Code + Codex Together¶

Best combo: Claude Code plans and reviews, Codex executes and automates.

QCode.cc: one plan, both tools share quota, zero switching cost. See Codex vs Claude Code Comparison for details.

10. FAQ¶

Q: Installation permission errors?

sudo npm install -g @anthropic-ai/claude-code
# Or use nvm (recommended)

Q: Connection timeout?

echo $ANTHROPIC_BASE_URL   # Should be https://asia.qcode.cc/api
curl -I https://asia.qcode.cc/api/health

Q: Cost concerns?

• Use Sonnet for daily work (60% cheaper than Opus)
• Use /cost to monitor spending
• Use Haiku for simple tasks

Q: Claude doesn't understand my project? Create a CLAUDE.md file — see Chapter 5.

Related Docs¶

• CLAUDE.md Configuration — Project config guide
• Hooks System — Automation hooks
• Automation & CI/CD — Headless mode
• Model Selection — Detailed model comparison
• Codex Complete Tutorial — Codex CLI guide
• Pricing Plans — QCode.cc plans