Question

Show: Create an application that allows the user to enter the number of calories and fat grams in a food. The application should display the percentage of the calories that come from fat. If the calories from fat are less than 30% of the total calories of the food, it should also display a message indicating the food is low in fat.

One gram of fat has 9 calories, so:

Calories from fat = fat grams *9

The percentage of calories from fat can be calculated as:

Percentage of calories from fat = Calories from fat / total calories

Input validation: Make sure the number of calories are not less than 0. Also, the number of calories from fat cannot be greater than the total number of calories. If that happens, display an error message indicating that either the calories or fat grams were incorrectly entered.

Use the following test data to determine if the application is calculating properly:

Calories and Fat Percentage

200 Calories, 8 fat grams Percentage of calories from fat: 36%

150 calories, 2 fat grams Percentage of calories from fat: 12%

(a low-fat food)

500 calories, 30 fat grams Percentage of calories from fat: 54%

VBA

Answer 1

Public Class Form1

    Dim calorie As Integer

    Dim fatInGram As Integer

    Dim percentage As Double

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

        lblOutput.Text = ""

        'Validate the input

        If ValidateInput() Then

            'calculate percentage

            percentage = (fatInGram * 9) / calorie

            'display in text box as %

            txtPercentage.Text = percentage.ToString("0.00%")

            'display the label in case of low fat food

            If percentage < 0.3 Then

                lblOutput.Text = "a low-fat food"

            End If

        End If

    End Sub

    Private Function ValidateInput()

        'if not able to parse in integer and calorie is less than 0 display error message

        If Not Integer.TryParse(txtCalorie.Text, calorie) OrElse calorie <= 0 Then

            MessageBox.Show("Invalid Calorie", "Fat Percentage Calculator", MessageBoxButtons.OK, MessageBoxIcon.Error)

            Return False

        End If

        'if not able to parse in integer and fat in Gram is less than 0 display error message

        If Not Integer.TryParse(txtgram.Text, fatInGram) OrElse fatInGram <= 0 Then

            MessageBox.Show("Invalid fat in gram", "Fat Percentage Calculator", MessageBoxButtons.OK, MessageBoxIcon.Error)

            Return False

        End If

        'if fat in gram * 9 is greater than calories then display error message

        If fatInGram * 9 > calorie Then

            MessageBox.Show("either the calories or fat grams were incorrectly entered", "Fat Percentage Calculator", MessageBoxButtons.OK, MessageBoxIcon.Error)

            Return False

        End If

        Return True

    End Function

    Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click

        txtPercentage.Clear()

        txtCalorie.Clear()

        txtgram.Clear()

        lblOutput.Text = ""

        txtCalorie.Focus()

    End Sub

    Private Sub btnExit_Click(sender As Object, e As EventArgs) Handles btnExit.Click

        Me.Close()

    End Sub

End Class

=========form1.designer.vb============

<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _

Partial Class Form1

    Inherits System.Windows.Forms.Form

    'Form overrides dispose to clean up the component list.

    <System.Diagnostics.DebuggerNonUserCode()> _

    Protected Overrides Sub Dispose(ByVal disposing As Boolean)

        Try

            If disposing AndAlso components IsNot Nothing Then

                components.Dispose()

            End If

        Finally

            MyBase.Dispose(disposing)

        End Try

    End Sub

    'Required by the Windows Form Designer

    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer

    'It can be modified using the Windows Form Designer.

    'Do not modify it using the code editor.

    <System.Diagnostics.DebuggerStepThrough()> _

    Private Sub InitializeComponent()

        Me.Label1 = New System.Windows.Forms.Label()

        Me.Label2 = New System.Windows.Forms.Label()

        Me.Label3 = New System.Windows.Forms.Label()

        Me.txtCalorie = New System.Windows.Forms.TextBox()

        Me.txtgram = New System.Windows.Forms.TextBox()

        Me.txtPercentage = New System.Windows.Forms.TextBox()

        Me.btnCalculate = New System.Windows.Forms.Button()

        Me.btnClear = New System.Windows.Forms.Button()

        Me.btnExit = New System.Windows.Forms.Button()

        Me.lblOutput = New System.Windows.Forms.Label()

        Me.SuspendLayout()

        '

        'Label1

        '

        Me.Label1.AutoSize = True

        Me.Label1.Location = New System.Drawing.Point(63, 55)

        Me.Label1.Name = "Label1"

        Me.Label1.Size = New System.Drawing.Size(292, 20)

        Me.Label1.TabIndex = 0

        Me.Label1.Text = "Enter the number of calories in the food:"

        Me.Label1.TextAlign = System.Drawing.ContentAlignment.MiddleRight

        '

        'Label2

        '

        Me.Label2.AutoSize = True

        Me.Label2.Location = New System.Drawing.Point(50, 108)

        Me.Label2.Name = "Label2"

        Me.Label2.Size = New System.Drawing.Size(305, 20)

        Me.Label2.TabIndex = 1

        Me.Label2.Text = "Enter the number of fat grams in the food:"

        Me.Label2.TextAlign = System.Drawing.ContentAlignment.MiddleRight

        '

        'Label3

        '

        Me.Label3.AutoSize = True

        Me.Label3.Location = New System.Drawing.Point(50, 167)

        Me.Label3.Name = "Label3"

        Me.Label3.Size = New System.Drawing.Size(305, 20)

        Me.Label3.TabIndex = 2

        Me.Label3.Text = "Percentage of calories that come from fat:"

        Me.Label3.TextAlign = System.Drawing.ContentAlignment.MiddleRight

        '

        'txtCalorie

        '

        Me.txtCalorie.Location = New System.Drawing.Point(361, 52)

        Me.txtCalorie.Name = "txtCalorie"

        Me.txtCalorie.Size = New System.Drawing.Size(188, 26)

        Me.txtCalorie.TabIndex = 3

        '

        'txtgram

        '

        Me.txtgram.Location = New System.Drawing.Point(361, 102)

        Me.txtgram.Name = "txtgram"

        Me.txtgram.Size = New System.Drawing.Size(188, 26)

        Me.txtgram.TabIndex = 4

        '

        'txtPercentage

        '

        Me.txtPercentage.Enabled = False

        Me.txtPercentage.Location = New System.Drawing.Point(361, 164)

        Me.txtPercentage.Name = "txtPercentage"

        Me.txtPercentage.Size = New System.Drawing.Size(188, 26)

        Me.txtPercentage.TabIndex = 5

        '

        'btnCalculate

        '

        Me.btnCalculate.Location = New System.Drawing.Point(68, 276)

        Me.btnCalculate.Name = "btnCalculate"

        Me.btnCalculate.Size = New System.Drawing.Size(172, 44)

        Me.btnCalculate.TabIndex = 6

        Me.btnCalculate.Text = "Calculate"

        Me.btnCalculate.UseVisualStyleBackColor = True

        '

        'btnClear

        '

        Me.btnClear.Location = New System.Drawing.Point(304, 276)

        Me.btnClear.Name = "btnClear"

        Me.btnClear.Size = New System.Drawing.Size(172, 44)

        Me.btnClear.TabIndex = 7

        Me.btnClear.Text = "Clear"

        Me.btnClear.UseVisualStyleBackColor = True

        '

        'btnExit

        '

        Me.btnExit.Location = New System.Drawing.Point(543, 276)

        Me.btnExit.Name = "btnExit"

        Me.btnExit.Size = New System.Drawing.Size(172, 44)

        Me.btnExit.TabIndex = 8

        Me.btnExit.Text = "Exit"

        Me.btnExit.UseVisualStyleBackColor = True

        '

        'lblOutput

        '

        Me.lblOutput.AutoSize = True

        Me.lblOutput.Location = New System.Drawing.Point(279, 230)

        Me.lblOutput.Name = "lblOutput"

        Me.lblOutput.Size = New System.Drawing.Size(0, 20)

        Me.lblOutput.TabIndex = 9

        '

        'Form1

        '

        Me.AutoScaleDimensions = New System.Drawing.SizeF(9.0!, 20.0!)

        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font

        Me.ClientSize = New System.Drawing.Size(800, 450)

        Me.Controls.Add(Me.lblOutput)

        Me.Controls.Add(Me.btnExit)

        Me.Controls.Add(Me.btnClear)

        Me.Controls.Add(Me.btnCalculate)

        Me.Controls.Add(Me.txtPercentage)

        Me.Controls.Add(Me.txtgram)

        Me.Controls.Add(Me.txtCalorie)

        Me.Controls.Add(Me.Label3)

        Me.Controls.Add(Me.Label2)

        Me.Controls.Add(Me.Label1)

        Me.Name = "Form1"

        Me.Text = "Fat Percentage Calculator"

        Me.ResumeLayout(False)

        Me.PerformLayout()

    End Sub

    Friend WithEvents Label1 As Label

    Friend WithEvents Label2 As Label

    Friend WithEvents Label3 As Label

    Friend WithEvents txtCalorie As TextBox

    Friend WithEvents txtgram As TextBox

    Friend WithEvents txtPercentage As TextBox

    Friend WithEvents btnCalculate As Button

    Friend WithEvents btnClear As Button

    Friend WithEvents btnExit As Button

    Friend WithEvents lblOutput As Label

End Class