Your First C# Windows Application

This example is to get you started creating Windows Forms applications in C# using SharpDevelop .

If you don't already have SharpDevelop , download and install it.

Create a new Combine and select a C# Windows Application Project.

Below the editor view, select the Design tab. Select the Form in the Form Designer and change the Text property to Calculator.

Add 3 TextBox and 4 Button Controls to the Form.

For the 3 TextBox controls, clear the Text property, and change the (Name) properties to Op1TextBox, Op2TextBox, and ResultTextBox. Change the text on the buttons to "+, -, *, & /". Change the (Name)s to "AddButton, SubtractButton, MultiplyButton, and DivideButton. Select all 4 buttons then adjust the Font property in the Properties Window.

Double click each button to create its event handler, then modify the code as shown here.

void AddButtonClick(object sender, System.EventArgs e)
{
   double dAns;
   dAns = double.Parse( Op1TextBox.Text ) + double.Parse( Op2TextBox.Text );
   ResultTextBox.Text = dAns.ToString();
}

void SubtractButtonClick(object sender, System.EventArgs e)
{
   double dAns;
   dAns = double.Parse( Op1TextBox.Text ) - double.Parse( Op2TextBox.Text );
   ResultTextBox.Text = dAns.ToString();
}

void MultiplyButtonClick(object sender, System.EventArgs e)
{
   double dAns;
   dAns = double.Parse( Op1TextBox.Text ) * double.Parse( Op2TextBox.Text );
   ResultTextBox.Text = dAns.ToString();
}

void DivideButtonClick(object sender, System.EventArgs e)
{
   double dAns;
   dAns = double.Parse( Op1TextBox.Text ) / double.Parse( Op2TextBox.Text );
   ResultTextBox.Text = dAns.ToString();
} 

Run the application and type values into the two operand text boxes. Click the four function button to test the application. This program has no error checking so if you give it invalid input it will crash.

Add some simple error handling.

void AddButtonClick(object sender, System.EventArgs e)
{
   double dAns;
   try
   {
      dAns = double.Parse( Op1TextBox.Text ) + double.Parse( Op2TextBox.Text );
      ResultTextBox.Text = dAns.ToString();
   }
   catch( Exception ex )
   {
      MessageBox.Show( ex.Message );
   }
}

void SubtractButtonClick(object sender, System.EventArgs e)
{
   double dAns;
   try
   {
      dAns = double.Parse( Op1TextBox.Text ) - double.Parse( Op2TextBox.Text );
      ResultTextBox.Text = dAns.ToString();
   }
   catch( Exception ex )
   {
      MessageBox.Show( ex.Message );
   }
}

void MultiplyButtonClick(object sender, System.EventArgs e)
{
   double dAns;
   try
   {
      dAns = double.Parse( Op1TextBox.Text ) * double.Parse( Op2TextBox.Text );
      ResultTextBox.Text = dAns.ToString();
   }
   catch( Exception ex )
   {
      MessageBox.Show( ex.Message );
   }
}

void DivideButtonClick(object sender, System.EventArgs e)
{
   double dAns;
   try
   {
      dAns = double.Parse( Op1TextBox.Text ) / double.Parse( Op2TextBox.Text );
      ResultTextBox.Text = dAns.ToString();
   }
   catch( Exception ex )
   {
      MessageBox.Show( ex.Message );
   }
}