Calculator Sample

This sample demonstrates the creation of a functional desktop calculator application using .NET technologies. It covers UI layout, event handling, and basic arithmetic operations.

Key Features:

Intuitive user interface resembling a standard calculator.
Support for basic arithmetic operations: addition, subtraction, multiplication, division.
Handling of decimal numbers.
Clear and clear-entry functionality.

Project Files:

The sample project consists of the following primary files:

CalculatorWindow.xaml: Defines the visual structure of the calculator using XAML.
CalculatorWindow.xaml.cs: Contains the C# code-behind for the calculator's logic.
App.xaml: The application entry point.

XAML Structure (`CalculatorWindow.xaml`):

The XAML defines the grid layout for the display and buttons. Here's a snippet of the button grid:

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto" />
        <RowDefinition Height="*" />
    </Grid.RowDefinitions>

    <!-- Display -->
    <TextBlock Grid.Row="0" Text="{Binding DisplayValue}" Style="{StaticResource DisplayStyle}" />

    <!-- Buttons -->
    <Grid Grid.Row="1" Margin="10">
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
            <ColumnDefinition />
            <ColumnDefinition />
            <ColumnDefinition />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
            <RowDefinition />
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>

        <Button Content="C" Grid.Column="0" Grid.Row="0" Command="{Binding ClearCommand}" />
        <Button Content="+/-" Grid.Column="1" Grid.Row="0" Command="{Binding SignChangeCommand}" />
        <Button Content="%" Grid.Column="2" Grid.Row="0" Command="{Binding PercentageCommand}" />
        <Button Content="/" Grid.Column="3" Grid.Row="0" Style="{StaticResource OperatorStyle}" Command="{Binding OperationCommand, ConverterParameter='/'}" />

        <Button Content="7" Grid.Column="0" Grid.Row="1" Command="{Binding NumberCommand, ConverterParameter='7'}" />
        <Button Content="8" Grid.Column="1" Grid.Row="1" Command="{Binding NumberCommand, ConverterParameter='8'}" />
        <Button Content="9" Grid.Column="2" Grid.Row="1" Command="{Binding NumberCommand, ConverterParameter='9'}" />
        <Button Content="*" Grid.Column="3" Grid.Row="1" Style="{StaticResource OperatorStyle}" Command="{Binding OperationCommand, ConverterParameter='*'}" />

        <!-- ... more buttons ... -->

        <Button Content="0" Grid.Column="0" Grid.Row="4" Grid.ColumnSpan="2" Style="{StaticResource ZeroButton}" Command="{Binding NumberCommand, ConverterParameter='0'}" />
        <Button Content="." Grid.Column="2" Grid.Row="4" Command="{Binding DecimalCommand}" />
        <Button Content="=" Grid.Column="3" Grid.Row="4" Style="{StaticResource EqualsStyle}" Command="{Binding EqualsCommand}" />
    </Grid>
</Grid>
            

C# Logic (`CalculatorWindow.xaml.cs`):

The code-behind handles button clicks, manages state, and performs calculations. Below is a simplified example of the number input logic:

public partial class CalculatorWindow : Window
{
    private string _currentInput = "0";
    private double _firstOperand = 0;
    private double? _secondOperand = null;
    private string _currentOperation = "";
    private bool _isNewEntry = true;

    public CalculatorWindow()
    {
        InitializeComponent();
        DisplayValue.Text = _currentInput;
    }

    private void NumberButton_Click(object sender, RoutedEventArgs e)
    {
        string digit = (sender as Button).Content.ToString();

        if (_isNewEntry)
        {
            _currentInput = digit;
            _isNewEntry = false;
        }
        else
        {
            if (_currentInput == "0")
            {
                _currentInput = digit;
            }
            else
            {
                _currentInput += digit;
            }
        }
        DisplayValue.Text = _currentInput;
    }

    private void OperationButton_Click(object sender, RoutedEventArgs e)
    {
        if (!string.IsNullOrEmpty(_currentOperation) && !_isNewEntry)
        {
            Calculate();
        }

        _firstOperand = double.Parse(_currentInput);
        _currentOperation = (sender as Button).Content.ToString();
        _isNewEntry = true;
    }

    private void EqualsButton_Click(object sender, RoutedEventArgs e)
    {
        Calculate();
        _currentOperation = "";
        _isNewEntry = true;
    }

    private void Calculate()
    {
        if (_secondOperand == null && !_isNewEntry)
        {
            _secondOperand = double.Parse(_currentInput);
        }

        double result = 0;
        switch (_currentOperation)
        {
            case "+":
                result = _firstOperand + _secondOperand.Value;
                break;
            case "-":
                result = _firstOperand - _secondOperand.Value;
                break;
            case "*":
                result = _firstOperand * _secondOperand.Value;
                break;
            case "/":
                if (_secondOperand.Value != 0)
                {
                    result = _firstOperand / _secondOperand.Value;
                }
                else
                {
                    DisplayValue.Text = "Error";
                    return;
                }
                break;
            default:
                result = _secondOperand.Value; // For cases like just pressing equals after a number
                break;
        }

        _currentInput = result.ToString();
        DisplayValue.Text = _currentInput;
        _firstOperand = result; // For chaining operations
        _secondOperand = null;
        _isNewEntry = true;
    }

    private void ClearButton_Click(object sender, RoutedEventArgs e)
    {
        _currentInput = "0";
        _firstOperand = 0;
        _secondOperand = null;
        _currentOperation = "";
        _isNewEntry = true;
        DisplayValue.Text = _currentInput;
    }

    // ... other event handlers for ., +/-, % ...
}
            

Live Demo:

Experience a simplified, interactive version of the calculator below: