Creating a Simple Command-Line Application

This example creates a simple command-line calculator.

import 'dart:io';

double add(double a, double b) => a + b;
double subtract(double a, double b) => a - b;
double multiply(double a, double b) => a * b;
double divide(double a, double b) {
  if (b == 0) {
throw Exception('Cannot divide by zero');
  }
  return a / b;
}

void main() {
  print('Simple Calculator');
  print('Enter two numbers:');
  
  var input1 = stdin.readLineSync();
  var input2 = stdin.readLineSync();
  
  double num1 = double.parse(input1!);
  double num2 = double.parse(input2!);
  
  print('Choose an operation: +, -, *, /');
  var operation = stdin.readLineSync();
  
  double result;
  switch (operation) {
case '+':
  result = add(num1, num2);
  break;
case '-':
  result = subtract(num1, num2);
  break;
case '*':
  result = multiply(num1, num2);
  break;
case '/':
  result = divide(num1, num2);
  break;
default:
  print('Invalid operation');
  return;
  }
  
  print('Result: $result');
}