C# Calculator

Question

Hi, I created a Calculator using Visual Studio C#. I added a backspace button for making it more convenient for users. But once I coded the button (Refer the image below for the code) and tested it did not work as expected. Example: When I tested by typing "543" number in textbox and pressed the backspace button, it erased the number "3" from "543" and the result was only "54" but when I pressed another number after backspacing for example "9", the number "3" appeared again resulting the output "5439". The "3" did not get erased. Please help!

Answer 1

For .NET Framework

public static class Extensions
{

    public static string TrimLastCharacter(this string sender) => 
        string.IsNullOrWhiteSpace(sender) ? 
            sender : 
            sender.TrimEnd(sender[sender.Length - 1]);
}

For .NET Framework Core 5 (Here note the ^1 which targets the last character in the string ^ is know as a hat.

public static class Extensions
{
    public static string TrimLastCharacter(this string sender) => 
        string.IsNullOrWhiteSpace(sender) ? 
            sender : 
            sender.TrimEnd(sender[^1]);
}

How to use

textBox1.Text = textBox1.Text.TrimLastCharacter();

Answer 2

I used your code to test but did not encounter the problem you mentioned.

        private void button1_Click(object sender, EventArgs e)  
        {  
            if (textBox1.Text.Length>0)  
            {  
                textBox1.Text = textBox1.Text.Remove(lastCharPosi, 1);  
            }  
            if (textBox1.Text=="")  
            {  
                textBox1.Text = "0";  
            }  
            MessageBox.Show(textBox1.Text);  
        }  
  
        private int lastCharPosi;  
        private void textBox1_TextChanged(object sender, EventArgs e)  
        {  
            lastCharPosi = textBox1.Text.Length-1;  
        }  

How do you define lastCharacterPosition?

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