InputBox.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace InaccuracyCalculator
{
    public static class InputDialog
    {
        public static DialogResult ShowInputDialog(ref string input)
    {
        System.Drawing.Size size = new System.Drawing.Size(200, 70);
        Form inputBox = new Form();

        inputBox.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog;
        inputBox.ClientSize = size;
        inputBox.Text = "Name";

        System.Windows.Forms.TextBox textBox = new TextBox();
        textBox.Size = new System.Drawing.Size(size.Width - 10, 23);
        textBox.Location = new System.Drawing.Point(5, 5);
        textBox.Text = input;
        inputBox.Controls.Add(textBox);

        Button okButton = new Button();
        okButton.DialogResult = System.Windows.Forms.DialogResult.OK;
        okButton.Name = "okButton";
        okButton.Size = new System.Drawing.Size(75, 23);
        okButton.Text = "&OK";
        okButton.Location = new System.Drawing.Point(size.Width - 80 - 80, 39);
        inputBox.Controls.Add(okButton);

        Button cancelButton = new Button();
        cancelButton.DialogResult = System.Windows.Forms.DialogResult.Cancel;
        cancelButton.Name = "cancelButton";
        cancelButton.Size = new System.Drawing.Size(75, 23);
        cancelButton.Text = "&Cancel";
        cancelButton.Location = new System.Drawing.Point(size.Width - 80, 39);
        inputBox.Controls.Add(cancelButton);

        inputBox.AcceptButton = okButton;
        inputBox.CancelButton = cancelButton;

        DialogResult result = inputBox.ShowDialog();
        input = textBox.Text;
        return result;
    }
}
}