🎯 Project: Personal Greeting App

📚 Lesson 1: Your First Dart App ⏱ 15-20 min 📊 Beginner

🎯 Objective

Build a command-line program that interacts with the user and performs basic calculations using everything you learned in Lesson 1.

Requirements

Create a new Dart file called greeting_app.dart in your project's bin folder
Ask for user's name using stdin.readLineSync() (you'll need to import 'dart:io';)
Ask for their age and convert it to an integer
Calculate approximate birth year using current year minus age
Print a personalized greeting including their name and calculated birth year
Handle invalid input (empty name, non-numeric age, unrealistic ages)
Add a fun message based on their age group (minor, adult, senior)

Expected Output

Terminal

=== Personal Greeting App ===

What is your name?
> Alice

How old are you?
> 25

Hello, Alice! 👋
You were born around the year 2001.
You are an adult. Perfect time to learn Dart!

Terminal (Error Handling)

=== Personal Greeting App ===

What is your name?
> 

Error: Name cannot be empty. Please try again.

Step-by-Step Hints

💡 Hint 1: Getting Started

Start with import 'dart:io'; at the top. This gives you access to stdin.readLineSync() for reading user input.

💡 Hint 2: Safe Number Conversion

Use int.tryParse(input) instead of int.parse(input). tryParse returns null if the conversion fails instead of throwing an error.

💡 Hint 3: Getting Current Year

Use DateTime.now().year to get the current year dynamically.

import 'dart:io'; void main() { print('=== Personal Greeting App ===\n'); // Step 1: Ask for name stdout.write('What is your name?\n> '); String? name = stdin.readLineSync(); // Step 2: Validate name input if (name == null || name.trim().isEmpty) { print('Error: Name cannot be empty. Please try again.'); return; // Exit the program } // Clean up the name (remove extra spaces) name = name.trim(); // Step 3: Ask for age stdout.write('\nHow old are you?\n> '); String? ageInput = stdin.readLineSync(); // Step 4: Validate age input if (ageInput == null || ageInput.trim().isEmpty) { print('Error: Age cannot be empty. Please try again.'); return; } // Step 5: Convert age to integer safely int? age = int.tryParse(ageInput.trim()); // Step 6: Check if age is valid if (age == null) { print('Error: "$ageInput" is not a valid number.'); return; } if (age < 0) { print('Error: Age cannot be negative.'); return; } if (age > 150) { print('Error: Please enter a realistic age (0-150).'); return; } // Step 7: Calculate approximate birth year int currentYear = DateTime.now().year; int birthYear = currentYear - age; // Step 8: Print personalized greeting print('\nHello, $name! 👋'); print('You were born around the year $birthYear.'); // Step 9: Add age-based fun message if (age < 13) { print('You are a child. It\'s amazing to start coding young!'); } else if (age < 18) { print('You are a teenager. Keep learning and building!'); } else if (age < 30) { print('You are a young adult. Perfect time to master Dart!'); } else if (age < 65) { print('You are an adult. It\'s never too late to learn programming!'); } else { print('You are a senior. Your experience is valuable in coding!'); } // Step 10: Additional information print('\n📊 Summary:'); print(' Name: $name'); print(' Age: $age'); print(' Birth Year (approx): $birthYear'); print(' Name length: ${name.length} characters'); // Bonus: Check if birth year is a leap year if (birthYear % 4 == 0 && (birthYear % 100 != 0 || birthYear % 400 == 0)) { print(' 🎂 You were born in a leap year!'); } }

Challenge: Extend the Project

Once you've completed the basic requirements, try these extensions:

Ask for the user's birth month and calculate a more accurate age
Calculate how many days until their next birthday
Store multiple users' information and display all at the end
Add color to the output using ANSI escape codes

🎉 Well Done!

You've completed your first Dart project! This demonstrates understanding of variables, user input, type conversion, conditional logic, and string interpolation - all fundamental Dart concepts.