使用按钮将数字添加到文本框

Question

I'm new to programming and I have a problem. I have two buttons and a textbox. When I press the button, a number will show on the textbox, but when I press the second button the number in the textbox overwrites it and replaces it instead of adding to it in the textbox. How do I fix this? I want the values to add instead of replacing it.

public partial class Form1 : Form
{
    int value1 = 0;
    int value2 = 0;
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        value1++;
        textBox1.Text = value1.ToString();
    }

    private void button2_Click(object sender, EventArgs e)
    {
        value2 += 2;
        textBox1.Text = value2.ToString();
    }
}

}

Answer 1

If you want to add two integers and assign the result back to textBox1 you have to

1. Parse textBox1.Text to integer: int.Parse(textBox1.Text)
2. Sum up values: int.Parse(textBox1.Text) + value2
3. Convert the outcome back to string : (...).ToString()

Implementation:

private void button2_Click(object sender, EventArgs e) { 
  value2 += 2;

  textBox1.Text = (int.Parse(textBox1.Text) + value2).ToString();
} 

Answer 2

You're using two separate variables ( value1 and value2 above) to store the results of each button click, depending in which button was clicked. Think of it like this:

On program start:
value1 = 0
value2 = 0

User clicks button 1, which executes button1_Click. This increments value1 (via value1++ ), so the two variables look like this:

value1 = 1
value2 = 0

User then clicks button 2, which executes button2_Click. This sets value2 to whatever was previously in value2 + 2. However, note that the value of value1 is unchanged:

value1 = 1
value2 = 2

By having separate variables, each button click is operating on a different value. I would modify your code so there is only one value variable that both _Click functions modify.

Answer 3

Add this line:

textBox1.Text = (int.parseInt(textBox1.Text) + value2).toString();

after

value2 += 2;

into your button2_click method: