Lab 1 — C Basics (Week 1)

Goals

• Set up a working C toolchain (GitHub Codespaces or local Linux with GCC + VS Code).
• Write, compile, and run simple C programs.
• Practice printf / scanf format specifiers.

Repository Layout

Lab01_C_Basics/
├─ src/
│  ├─ hello.c
│  ├─ calculator.c
│  └─ format_specifiers.c
├─ include/
├─ bin/                # compiled binaries land here
├─ .vscode/            # VS Code tasks & debug config
├─ .devcontainer/      # one-click Codespaces
├─ Makefile
├─ .gitignore
├─ LICENSE (MIT)
└─ README.md

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Option A — Run in GitHub Codespaces (recommended)

1. Push this repo to GitHub and click Code → Codespaces → Create codespace on main.
2. The provided devcontainer will provision a C/C++ environment (GCC, GDB, Make).
3. Open the Terminal in VS Code (inside Codespaces) and run:

make            # builds all targets
./bin/hello
./bin/calculator
./bin/formats

Or use the pre-configured VS Code Tasks:

• Build All (Make) — builds all targets
• Run: Hello — builds and runs hello
• Run: Calculator — builds and runs calculator
• Run: Formats — builds and runs formats

Debugging:

• Put a breakpoint in src/hello.c
• Run Start Debugging (Hello) from the Run/Debug panel

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Option B — Run locally on Linux (or WSL)

1. Install build tools:

   sudo apt update && sudo apt install -y build-essential gdb

2. Build with make:

   make
   ./bin/hello
   ./bin/calculator
   ./bin/formats

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Targets (via make)

• make or make all — build all programs
• make hello — build Hello, World
• make calculator — build calculator
• make formats — build format specifier demo
• make clean — remove build artifacts

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Programs

1) hello.c

• Prints a greeting and shows command-line arguments (if any).

2) calculator.c

• Simple arithmetic calculator (sum, difference, product, quotient).
• Demonstrates input validation and division-by-zero handling.

3) format_specifiers.c

• Demonstrates key printf/scanf format specifiers:
  • Integers: %d, %u, %x, %o
  • Characters: %c
  • Floats: %f, %e, precision like %.2f
  • Strings: %s (single word), fgets for full line input
  • Field width & alignment basics

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Sample Commands

# Build everything
make

# Run Hello (with arguments)
./bin/hello Alice 42

# Run Calculator
./bin/calculator

# Run Format Specifiers demo
./bin/formats

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Notes on scanf

• scanf("%d", &x) reads an integer; always pass the address-of &x.
• After numeric scanf, there may be a leftover newline \n in the buffer. Use getchar() or prefer fgets() + sscanf() for robust input.

Happy hacking! 🎯