Question

OBJECTIVE C

2) // Create a small app that takes user input and performs a useful calculation with that user input

// - make sure that absolutely no input crashes the app.

// - Use layout constraints to make sure the app looks good in portraint and landscape mode, as well as on small and large devices.

Answer 1

using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Text;
    using System.Windows.Forms;
    
    namespace CalculatorApp
    {
        public partial class Form1 : Form
        {
            double FirstNumber;
            string Operation;
            public Form1()
            {
                InitializeComponent();
            }
    
           
            private void n1_Click(object sender, EventArgs e)
            {
                if (textBox1.Text == "0" && textBox1.Text != null)
                {
                    textBox1.Text = "1";
                }
                else
                {
                    textBox1.Text = textBox1.Text + "1";
                }
            }
    
            private void n2_Click(object sender, EventArgs e)
            {
                if (textBox1.Text == "0" && textBox1.Text != null)
                {
                    textBox1.Text = "2";
                }
                else
                {
                    textBox1.Text = textBox1.Text + "2";
                }
            }
    
            private void n3_Click(object sender, EventArgs e)
            {
                if (textBox1.Text == "0" && textBox1.Text != null)
                {
                    textBox1.Text = "3";
                }
                else
                {
                    textBox1.Text = textBox1.Text + "3";
                }
            }
    
            private void n4_Click(object sender, EventArgs e)
            {
                if (textBox1.Text == "0" && textBox1.Text != null)
                {
                    textBox1.Text = "4";
                }
                else
                {
                    textBox1.Text = textBox1.Text + "4";
                }
            }
    
            private void n5_Click(object sender, EventArgs e)
            {
                if (textBox1.Text == "0" && textBox1.Text != null)
                {
                    textBox1.Text = "5";
                }
                else
                {
                    textBox1.Text = textBox1.Text + "5";
                }
            }
    
            private void n6_Click(object sender, EventArgs e)
            {
                if (textBox1.Text == "0" && textBox1.Text != null)
                {
                    textBox1.Text = "6";
                }
                else
                {
                    textBox1.Text = textBox1.Text + "6";
                }
            }
    
            private void n7_Click(object sender, EventArgs e)
            {
                if (textBox1.Text == "0" && textBox1.Text != null)
                {
                    textBox1.Text = "7";
                }
                else
                {
                    textBox1.Text = textBox1.Text + "7";
                }
            }
    
            private void n8_Click(object sender, EventArgs e)
            {
                if (textBox1.Text == "0" && textBox1.Text != null)
                {
                    textBox1.Text = "8";
                }
                else
                {
                    textBox1.Text = textBox1.Text + "8";
                }
            }
    
            private void n9_Click(object sender, EventArgs e)
            {
                if (textBox1.Text == "" && textBox1.Text != null)
                {
                    textBox1.Text = "9";
                }
                else
                {
                    textBox1.Text = textBox1.Text + "9";
                }
            }
    
            private void n0_Click(object sender, EventArgs e)
            {
                textBox1.Text = textBox1.Text + "0";
            }
    
            private void bad_Click(object sender, EventArgs e)
            {
                FirstNumber = Convert.ToDouble(textBox1.Text);
                textBox1.Text = "0";
                Operation = "+";
            }
    
            private void bsub_Click(object sender, EventArgs e)
            {
                FirstNumber = Convert.ToDouble(textBox1.Text);
                textBox1.Text = "0";
                Operation = "-";
    
            }
    
            private void bmul_Click(object sender, EventArgs e)
            {
                FirstNumber = Convert.ToDouble(textBox1.Text);
                textBox1.Text = "0";
                Operation = "*";
            }
    
            private void bdiv_Click(object sender, EventArgs e)
            {
                FirstNumber = Convert.ToDouble(textBox1.Text);
                textBox1.Text = "0";
                Operation = "/";
            }
    
            private void bc_Click(object sender, EventArgs e)
            {
                textBox1.Text = "0";
            }
    
            private void ndot_Click(object sender, EventArgs e)
            {
                textBox1.Text = textBox1.Text + ".";
            }
    
            private void nequal_Click(object sender, EventArgs e)
            {
                double SecondNumber;
                double Result;
    
                SecondNumber = Convert.ToDouble(textBox1.Text);
    
                if (Operation == "+")
                {
                    Result = (FirstNumber + SecondNumber);
                    textBox1.Text = Convert.ToString(Result);
                    FirstNumber = Result;
                }
                if (Operation == "-")
                {
                    Result = (FirstNumber - SecondNumber);
                    textBox1.Text = Convert.ToString(Result);
                    FirstNumber = Result;
                }
                if (Operation == "*")
                {
                    Result = (FirstNumber * SecondNumber);
                    textBox1.Text = Convert.ToString(Result);
                    FirstNumber = Result;
                }
                if (Operation == "/")
                {
                    if (SecondNumber == 0)
                    {
                        textBox1.Text = "Cannot divide by zero";
    
                    }
                    else
                    {
                        Result = (FirstNumber / SecondNumber);
                        textBox1.Text = Convert.ToString(Result);
                        FirstNumber = Result;
                    }
                }
            }
        }
    }