C# Windows 窗体应用程序 - 如何从文本框中获取用户输入

Question

I'm confused on what I'm supposed to use to get a users input.
I have 2 TextBoxes and a Button and I want to take what the user enters in those 2 TextBoxes and use it to calculate the total when the button is pushed.
I already have 3 variables declared: one for 1st input, one for the 2nd input, and one for the total of the two.

double length;
double width;
double area;

area =((length*length)+(width)(width));

I have this code inside of an event handler that will calculate the area when the Button is clicked. C# is new for me, I remember in Java you can use a scanner but I'm not sure what you can use here.

Answer 1

The TextBox control has a Text property . You would simply reference that to get the value out of the TextBox .

Note that in the following example, I'm making assumptions about the names of your controls since you didn't provide them.

private void CalculateBtn_Click(object sender, EventArgs e)
{
   string lengthString = LengthTxt.Text;
   string widthString = WidthTxt.Text;
}

You'll notice that the Text property returns a string . You'll need to parse that into a number to do the actual calculations. By using, for example, Double.Parse or Double.TryParse .

Since you're taking user input, you should use Double.TryParse . A TextBox will take any string , after all. Not just string s that parse to a double .

private void CalculateBtn_Click(object sender, EventArgs e)
{
   if (!double.TryParse(LengthTxt.Text, out double length))
   {
      MessageBox.Show("Please enter a number for the length.");
      return;
   }
   if (!double.TryParse(Width.Text, out double width))
   {
      MessageBox.Show("Please enter a number for the width.");
      return;
   }
}

Answer 2

Click on one of the box and you should see the properties tab on the bottom right. Search for the (Name) property under "Design" and set a name such as "length". In the EventHandler, get the string value with (the name of your box).Text and you can use a method such as Int32.Parse(string) to convert it to an int.