Question

Project 10-1 Convert lengths In this assignment, you’ll add code to a form that converts the value the user enters based on the selected conversion type. The application should handle the following conversions:

From To Conversion

Miles - Kilometers: 1 mile = 1.6093 kilometers

Kilometers - Miles: 1 kilometer = 0.6214 miles

Feet - Meters: 1 foot = 0.3048 meters

Meters - Feet: 1 meter = 3.2808 feet

Inches - Centimeters: 1 inch = 2.54 centimeters

Centimeters - Inches: 1 centimeter = 0.3937 inches

Feet - Yards: 1 foot = 0.333333 yards

Yards - Feet: 1 yard = 3 feet

1. Open the Conversions project. Display the code for the form, and notice the rectangular array whose rows contain the value to be displayed in the combo box, the text for the labels that identify the two text boxes, and the multiplier for the conversion as shown above.

2. Set the DropDownStyle property of the combo box so the user must select an item from the list.

3. Add the 2 additional conversion units for feet and yards to the array.

4. Add code to load the combo box (use the load event) with the first element in each row of the rectangular array a. display the first item in the combo box when the form is loaded. (I need to figure out how to grab from the array and not from a list)

5. Add code to: a. change the labels for the text boxes (When the user selects a conversion, the label for the textboxes should reflect that selection.) b. clear the calculated length c. move the focus to the entry text box when the user selects a different item from the combo box.

6. Rename the form to frmConversions.

7. Test the application to be sure the conversions are displayed in the combo box, the first conversion is selected by default, and the labels change appropriately when a different conversion is selected.

8. Add code to calculate and display the converted length when the user clicks the Calculate button. To calculate the length, you can get the index for the selected conversion and then use that index to get the multiplier from the array. Test the application to be sure this works correctly.

9. Add code to check that the user enters a valid decimal value for the length. Then, test the application one more time to be sure the validation works correctly.

Code Given:

Public Class frmConversions

Dim conversionTable(,) As String = {
{"Miles to kilometers", "Miles", "Kilometers", "1.6093"},
{"Kilometers to miles", "Kilometers", "Miles", "0.6214"},
{"Feet to meters", "Feet", "Meters", "0.3048"},
{"Meters to feet", "Meters", "Feet", "3.2808"},
{"Inches to centimeters", "Inches", "Centimeters", "2.54"},
{"Centimeters to inches", "Centimeters", "Inches", "0.3937"},
{"Feet to Yards", "Feet", "Yards", " 0.333333"},
{"Yards to Feet", "Yards", "Feet", "3"}}

Public Function IsPresent(ByVal textbox As TextBox, ByVal name As String) _
As Boolean
If textbox.Text = "" Then
MessageBox.Show(name & " is a required field.", "Entry Error")
textbox.Select()
Return False
Else
Return True
End If
End Function

Public Function IsDecimal(ByVal textbox As TextBox, ByVal name As String) _
As Boolean
Dim number As Decimal = 0
If Decimal.TryParse(textbox.Text, number) Then
Return True
Else
MessageBox.Show(name & " must be a decimal value.", "Entry Error")
textbox.Select()
textbox.SelectAll()
Return False
End If
End Function

Private Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnCalculate.Click

End Sub

Private Sub cboConversions_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cboConversions.SelectedIndexChanged

End Sub

Private Sub btnExit_Click(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles btnExit.Click
Me.Close()
End Sub

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

End Sub

Answer 1

Form1.Designer.cs

namespace Conversions
{
partial class Form1
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;

/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}

#region Windows Form Designer generated code

/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.lblCalculatedLength = new System.Windows.Forms.Label();
this.txtLength = new System.Windows.Forms.TextBox();
this.lblToLength = new System.Windows.Forms.Label();
this.lblFromLength = new System.Windows.Forms.Label();
this.btnExit = new System.Windows.Forms.Button();
this.btnCalculate = new System.Windows.Forms.Button();
this.cboConversions = new System.Windows.Forms.ComboBox();
this.Label1 = new System.Windows.Forms.Label();
this.SuspendLayout();
//
// lblCalculatedLength
//
this.lblCalculatedLength.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
this.lblCalculatedLength.Location = new System.Drawing.Point(94, 76);
this.lblCalculatedLength.Name = "lblCalculatedLength";
this.lblCalculatedLength.Size = new System.Drawing.Size(96, 20);
this.lblCalculatedLength.TabIndex = 30;
this.lblCalculatedLength.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
//
// txtLength
//
this.txtLength.Location = new System.Drawing.Point(94, 44);
this.txtLength.Name = "txtLength";
this.txtLength.Size = new System.Drawing.Size(96, 20);
this.txtLength.TabIndex = 25;
//
// lblToLength
//
this.lblToLength.Location = new System.Drawing.Point(14, 76);
this.lblToLength.Name = "lblToLength";
this.lblToLength.Size = new System.Drawing.Size(72, 23);
this.lblToLength.TabIndex = 29;
this.lblToLength.Text = "Kilometers:";
this.lblToLength.TextAlign = System.Drawing.ContentAlignment.MiddleRight;
//
// lblFromLength
//
this.lblFromLength.Location = new System.Drawing.Point(14, 44);
this.lblFromLength.Name = "lblFromLength";
this.lblFromLength.Size = new System.Drawing.Size(72, 23);
this.lblFromLength.TabIndex = 28;
this.lblFromLength.Text = "Miles:";
this.lblFromLength.TextAlign = System.Drawing.ContentAlignment.MiddleRight;
//
// btnExit
//
this.btnExit.CausesValidation = false;
this.btnExit.DialogResult = System.Windows.Forms.DialogResult.Cancel;
this.btnExit.Location = new System.Drawing.Point(158, 116);
this.btnExit.Name = "btnExit";
this.btnExit.Size = new System.Drawing.Size(80, 23);
this.btnExit.TabIndex = 27;
this.btnExit.Text = "E&xit";
this.btnExit.Click += new System.EventHandler(this.btnExit_Click);
//
// btnCalculate
//
this.btnCalculate.Location = new System.Drawing.Point(30, 116);
this.btnCalculate.Name = "btnCalculate";
this.btnCalculate.Size = new System.Drawing.Size(80, 23);
this.btnCalculate.TabIndex = 26;
this.btnCalculate.Text = "&Calculate";
this.btnCalculate.Click += new System.EventHandler(this.btnCalculate_Click);
//
// cboConversions
//
this.cboConversions.DropDownWidth = 160;
this.cboConversions.Location = new System.Drawing.Point(94, 12);
this.cboConversions.Name = "cboConversions";
this.cboConversions.Size = new System.Drawing.Size(144, 21);
this.cboConversions.TabIndex = 24;
this.cboConversions.SelectedIndexChanged += new System.EventHandler(this.cboConversions_SelectedIndexChanged);
//
// Label1
//
this.Label1.Location = new System.Drawing.Point(14, 12);
this.Label1.Name = "Label1";
this.Label1.Size = new System.Drawing.Size(72, 23);
this.Label1.TabIndex = 23;
this.Label1.Text = "Conversion:";
this.Label1.TextAlign = System.Drawing.ContentAlignment.MiddleRight;
//
// Form1
//
this.AcceptButton = this.btnCalculate;
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.CancelButton = this.btnExit;
this.ClientSize = new System.Drawing.Size(261, 155);
this.Controls.Add(this.lblCalculatedLength);
this.Controls.Add(this.txtLength);
this.Controls.Add(this.lblToLength);
this.Controls.Add(this.lblFromLength);
this.Controls.Add(this.btnExit);
this.Controls.Add(this.btnCalculate);
this.Controls.Add(this.cboConversions);
this.Controls.Add(this.Label1);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
this.Name = "Form1";
this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
this.Text = "Conversions";
this.Load += new System.EventHandler(this.Form1_Load);
this.ResumeLayout(false);
this.PerformLayout();

}

#endregion

internal System.Windows.Forms.Label lblCalculatedLength;
internal System.Windows.Forms.TextBox txtLength;
internal System.Windows.Forms.Label lblToLength;
internal System.Windows.Forms.Label lblFromLength;
internal System.Windows.Forms.Button btnExit;
internal System.Windows.Forms.Button btnCalculate;
internal System.Windows.Forms.ComboBox cboConversions;
internal System.Windows.Forms.Label Label1;
}
}

Form1.cs

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

namespace Conversions
{
public partial class Form1 : Form
{
//declare a rectangular array to store items
private static string[,] comboItems = new string[6, 2];
public Form1()
{
InitializeComponent();
}

private void btnExit_Click(object sender, EventArgs e)
{
this.Close();
}

private void Form1_Load(object sender, EventArgs e)
{
//add items to the array
comboItems[0, 0] = "Miles to Kilometers";
comboItems[0, 1] = "1.6093";
comboItems[1, 0] = "Kilometers to miles";
comboItems[1, 1] = "0.6214";
comboItems[2, 0] = "Feet to meters";
comboItems[2, 1] = "0.3048";
comboItems[3, 0] = "Meters to feet";
comboItems[3, 1] = "3.2808";
comboItems[4, 0] = "Inches to Centimeters";
comboItems[4, 1] = "2.54";
comboItems[5, 0] = "Centimeters to inches";
comboItems[0, 1] = "0.3937";
//add the items to the combo box
for (int i = 0; i < comboItems.GetLength(0); i++)
{
cboConversions.Items.Add(comboItems[i, 0]);
}
//select the first item on form load
cboConversions.SelectedIndex = 0;
}

private void cboConversions_SelectedIndexChanged(object sender, EventArgs e)
{
//change the text of labels and clear the textboxes based on items selected in the combo box
if (cboConversions.SelectedIndex == 0)
{
lblFromLength.Text = "Miles: ";
lblToLength.Text = "Kilometers: ";
lblCalculatedLength.Text = "";
txtLength.Text = "";
}
else if (cboConversions.SelectedIndex == 1)
{
lblFromLength.Text = "Kilometers: ";
lblToLength.Text = "Miles: ";
lblCalculatedLength.Text = "";
txtLength.Text = "";
}
else if (cboConversions.SelectedIndex == 2)
{
lblFromLength.Text = "Feet: ";
lblToLength.Text = "Meters: ";
lblCalculatedLength.Text = "";
txtLength.Text = "";
}
else if (cboConversions.SelectedIndex == 3)
{
lblFromLength.Text = "Meters: ";
lblToLength.Text = "Feet: ";
lblCalculatedLength.Text = "";
txtLength.Text = "";
}
else if (cboConversions.SelectedIndex == 4)
{
lblFromLength.Text = "Inches: ";
lblToLength.Text = "Centimeters: ";
lblCalculatedLength.Text = "";
txtLength.Text = "";
}
else if (cboConversions.SelectedIndex == 5)
{
lblFromLength.Text = "Centimeters: ";
lblToLength.Text = "Inches: ";
lblCalculatedLength.Text = "";
txtLength.Text = "";
}

}

private void btnCalculate_Click(object sender, EventArgs e)
{
double lengthToBeConverted;
double convertedLength;
//check if iniput is valid
if (Double.TryParse(txtLength.Text, out lengthToBeConverted))
{
//convert the length and display it
convertedLength = lengthToBeConverted * Convert.ToDouble(comboItems[cboConversions.SelectedIndex, 1]);
lblCalculatedLength.Text = convertedLength.ToString("0.00");
}
//display error message when invalid input is entered
else
{
MessageBox.Show("Invalid input.", "Error");
txtLength.Focus();
}
}
}
}

Output Screens:-

Form1.Designer.cs

namespace Conversions
{
partial class Form1
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;

/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}

#region Windows Form Designer generated code

/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.lblCalculatedLength = new System.Windows.Forms.Label();
this.txtLength = new System.Windows.Forms.TextBox();
this.lblToLength = new System.Windows.Forms.Label();
this.lblFromLength = new System.Windows.Forms.Label();
this.btnExit = new System.Windows.Forms.Button();
this.btnCalculate = new System.Windows.Forms.Button();
this.cboConversions = new System.Windows.Forms.ComboBox();
this.Label1 = new System.Windows.Forms.Label();
this.SuspendLayout();
//
// lblCalculatedLength
//
this.lblCalculatedLength.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
this.lblCalculatedLength.Location = new System.Drawing.Point(94, 76);
this.lblCalculatedLength.Name = "lblCalculatedLength";
this.lblCalculatedLength.Size = new System.Drawing.Size(96, 20);
this.lblCalculatedLength.TabIndex = 30;
this.lblCalculatedLength.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
//
// txtLength
//
this.txtLength.Location = new System.Drawing.Point(94, 44);
this.txtLength.Name = "txtLength";
this.txtLength.Size = new System.Drawing.Size(96, 20);
this.txtLength.TabIndex = 25;
//
// lblToLength
//
this.lblToLength.Location = new System.Drawing.Point(14, 76);
this.lblToLength.Name = "lblToLength";
this.lblToLength.Size = new System.Drawing.Size(72, 23);
this.lblToLength.TabIndex = 29;
this.lblToLength.Text = "Kilometers:";
this.lblToLength.TextAlign = System.Drawing.ContentAlignment.MiddleRight;
//
// lblFromLength
//
this.lblFromLength.Location = new System.Drawing.Point(14, 44);
this.lblFromLength.Name = "lblFromLength";
this.lblFromLength.Size = new System.Drawing.Size(72, 23);
this.lblFromLength.TabIndex = 28;
this.lblFromLength.Text = "Miles:";
this.lblFromLength.TextAlign = System.Drawing.ContentAlignment.MiddleRight;
//
// btnExit
//
this.btnExit.CausesValidation = false;
this.btnExit.DialogResult = System.Windows.Forms.DialogResult.Cancel;
this.btnExit.Location = new System.Drawing.Point(158, 116);
this.btnExit.Name = "btnExit";
this.btnExit.Size = new System.Drawing.Size(80, 23);
this.btnExit.TabIndex = 27;
this.btnExit.Text = "E&xit";
this.btnExit.Click += new System.EventHandler(this.btnExit_Click);
//
// btnCalculate
//
this.btnCalculate.Location = new System.Drawing.Point(30, 116);
this.btnCalculate.Name = "btnCalculate";
this.btnCalculate.Size = new System.Drawing.Size(80, 23);
this.btnCalculate.TabIndex = 26;
this.btnCalculate.Text = "&Calculate";
this.btnCalculate.Click += new System.EventHandler(this.btnCalculate_Click);
//
// cboConversions
//
this.cboConversions.DropDownWidth = 160;
this.cboConversions.Location = new System.Drawing.Point(94, 12);
this.cboConversions.Name = "cboConversions";
this.cboConversions.Size = new System.Drawing.Size(144, 21);
this.cboConversions.TabIndex = 24;
this.cboConversions.SelectedIndexChanged += new System.EventHandler(this.cboConversions_SelectedIndexChanged);
//
// Label1
//
this.Label1.Location = new System.Drawing.Point(14, 12);
this.Label1.Name = "Label1";
this.Label1.Size = new System.Drawing.Size(72, 23);
this.Label1.TabIndex = 23;
this.Label1.Text = "Conversion:";
this.Label1.TextAlign = System.Drawing.ContentAlignment.MiddleRight;
//
// Form1
//
this.AcceptButton = this.btnCalculate;
this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.CancelButton = this.btnExit;
this.ClientSize = new System.Drawing.Size(261, 155);
this.Controls.Add(this.lblCalculatedLength);
this.Controls.Add(this.txtLength);
this.Controls.Add(this.lblToLength);
this.Controls.Add(this.lblFromLength);
this.Controls.Add(this.btnExit);
this.Controls.Add(this.btnCalculate);
this.Controls.Add(this.cboConversions);
this.Controls.Add(this.Label1);
this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
this.Name = "Form1";
this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
this.Text = "Conversions";
this.Load += new System.EventHandler(this.Form1_Load);
this.ResumeLayout(false);
this.PerformLayout();

}

#endregion

internal System.Windows.Forms.Label lblCalculatedLength;
internal System.Windows.Forms.TextBox txtLength;
internal System.Windows.Forms.Label lblToLength;
internal System.Windows.Forms.Label lblFromLength;
internal System.Windows.Forms.Button btnExit;
internal System.Windows.Forms.Button btnCalculate;
internal System.Windows.Forms.ComboBox cboConversions;
internal System.Windows.Forms.Label Label1;
}
}

Form1.cs

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

namespace Conversions
{
public partial class Form1 : Form
{
//declare a rectangular array to store items
private static string[,] comboItems = new string[6, 2];
public Form1()
{
InitializeComponent();
}

private void btnExit_Click(object sender, EventArgs e)
{
this.Close();
}

private void Form1_Load(object sender, EventArgs e)
{
//add items to the array
comboItems[0, 0] = "Miles to Kilometers";
comboItems[0, 1] = "1.6093";
comboItems[1, 0] = "Kilometers to miles";
comboItems[1, 1] = "0.6214";
comboItems[2, 0] = "Feet to meters";
comboItems[2, 1] = "0.3048";
comboItems[3, 0] = "Meters to feet";
comboItems[3, 1] = "3.2808";
comboItems[4, 0] = "Inches to Centimeters";
comboItems[4, 1] = "2.54";
comboItems[5, 0] = "Centimeters to inches";
comboItems[0, 1] = "0.3937";
//add the items to the combo box
for (int i = 0; i < comboItems.GetLength(0); i++)
{
cboConversions.Items.Add(comboItems[i, 0]);
}
//select the first item on form load
cboConversions.SelectedIndex = 0;
}

private void cboConversions_SelectedIndexChanged(object sender, EventArgs e)
{
//change the text of labels and clear the textboxes based on items selected in the combo box
if (cboConversions.SelectedIndex == 0)
{
lblFromLength.Text = "Miles: ";
lblToLength.Text = "Kilometers: ";
lblCalculatedLength.Text = "";
txtLength.Text = "";
}
else if (cboConversions.SelectedIndex == 1)
{
lblFromLength.Text = "Kilometers: ";
lblToLength.Text = "Miles: ";
lblCalculatedLength.Text = "";
txtLength.Text = "";
}
else if (cboConversions.SelectedIndex == 2)
{
lblFromLength.Text = "Feet: ";
lblToLength.Text = "Meters: ";
lblCalculatedLength.Text = "";
txtLength.Text = "";
}
else if (cboConversions.SelectedIndex == 3)
{
lblFromLength.Text = "Meters: ";
lblToLength.Text = "Feet: ";
lblCalculatedLength.Text = "";
txtLength.Text = "";
}
else if (cboConversions.SelectedIndex == 4)
{
lblFromLength.Text = "Inches: ";
lblToLength.Text = "Centimeters: ";
lblCalculatedLength.Text = "";
txtLength.Text = "";
}
else if (cboConversions.SelectedIndex == 5)
{
lblFromLength.Text = "Centimeters: ";
lblToLength.Text = "Inches: ";
lblCalculatedLength.Text = "";
txtLength.Text = "";
}

}

private void btnCalculate_Click(object sender, EventArgs e)
{
double lengthToBeConverted;
double convertedLength;
//check if iniput is valid
if (Double.TryParse(txtLength.Text, out lengthToBeConverted))
{
//convert the length and display it
convertedLength = lengthToBeConverted * Convert.ToDouble(comboItems[cboConversions.SelectedIndex, 1]);
lblCalculatedLength.Text = convertedLength.ToString("0.00");
}
//display error message when invalid input is entered
else
{
MessageBox.Show("Invalid input.", "Error");
txtLength.Focus();
}
}
}
}

Output Screens