Visual C# Examples: Red Oak High School

	Visual C# Examples: Red Oak High School - Grades

Introduction

This exercise is meant to apply the theories reviewed in file processing. It simulates taking the grades of a student and saving them to a file. It also provides the ability to open a previously saved record of a student. For this exercise, we use the FileStream class.

Practical Learning: Introducing File Streaming

Create a new Windows Forms Application named ROSH1

Design the form as follows:

Control	Name	Text	Other Properties
GroupBox		Identification
Label		Student Name:
TextBox	txtStudentName
Label		School Year:
TextBox	txtSchoolYear1
Label		/
TextBox	txtSchoolYear2
GroupBox		Grades
Label		English:
TextBox	txtEnglish	0.00	TextAlign: Right
Label		History:
TextBox	txtHistory	0.00	TextAlign: Right
Label		Economics:
TextBox	txtEconomics	0.00	TextAlign: Right
Label		2nd Language:
TextBox	txt2ndLanguage	0.00	TextAlign: Right
Label		Geography:
TextBox	txtGeography	0.00	TextAlign: Right
Label		Arts:
TextBox	txtArts	0.00	TextAlign: Right
Label		Math:
TextBox	txtMath	0.00	TextAlign: Right
Label		Science:
TextBox	txtScience	0.00	TextAlign: Right
Label		Phys Educ:
TextBox	txtPhysEduc	0.00	TextAlign: Right
GroupBox		Grade Processing
Button	btnCalculate	Calculate
Label		Total:
TextBox	txtTotal	0.00	TextAlign: Right
Label		Average:
TextBox	txtAverage	0.00	TextAlign: Right
Button	btnSave	Save
Button	btnOpen	Open
Button	btnClose	Close

Double-click the Calculate button and implement its Click event as follows:

private void btnCalculate_Click(object sender, System.EventArgs e)
{
	 decimal english = 0, history = 0, economics = 0, language2 = 0,
		     geography = 0, arts = 0, math = 0, science = 0,
		     physEduc = 0, total = 0, average = 0;

	 // Retrieve the value entered for each course
	 try {
		 english = decimal.Parse(this.txtEnglish.Text);
	 }
	 catch(FormatException )
	 {
		 MessageBox.Show("The value you entered for the English course is not valid");
		 this.txtEnglish.Focus();
	 }

	 try {
		 history = decimal.Parse(this.txtHistory.Text);
	 }
	 catch(FormatException )
	 {
		 MessageBox.Show("The value you entered for the History course is not valid");
		 this.txtEnglish.Focus();
	 }
			 
	 try {
		 economics = decimal.Parse(this.txtEconomics.Text);
	 }
	 catch(FormatException )
	 {
		 MessageBox.Show("The value you entered for the Economics course is not valid");
		 this.txtEnglish.Focus();
	 }
			 
	 try {
		 language2 = decimal.Parse(this.txt2ndLanguage.Text);
	 }
	 catch(FormatException )
	 {
		 MessageBox.Show("The value you entered for the 2nd Language course is not valid");
		 this.txtEnglish.Focus();
	 }
			 
	 try {
		 geography = decimal.Parse(this.txtGeography.Text);
	 }
	 catch(FormatException )
	 {
		 MessageBox.Show("The value you entered for the Geography course is not valid");
		 this.txtEnglish.Focus();
	 }
			 
	 try {
		 arts = decimal.Parse(this.txtArts.Text);
	 }
	 catch(FormatException )
	 {
		 MessageBox.Show("The value you entered for the Arts course is not valid");
		 this.txtEnglish.Focus();
	 }
			 
	 try {
		 math = decimal.Parse(this.txtMath.Text);
	 }
	 catch(FormatException )
	 {
		 MessageBox.Show("The value you entered for the Math course is not valid");
		 this.txtEnglish.Focus();
	 }
			 
	 try {
		 science = decimal.Parse(this.txtScience.Text);
	 }
	 catch(FormatException )
	 {
		 MessageBox.Show("The value you entered for the Science course is not valid");
		 this.txtEnglish.Focus();
	 }
			 
	 try {
		 physEduc = decimal.Parse(this.txtPhysEduc.Text);
	 }
	 catch(FormatException )
	 {
		 MessageBox.Show("The value you entered for the Physical Education course is not valid");
		 this.txtEnglish.Focus();
	 }

	 // Calculate the total and the average
	 total = english + history + economics + language2 +
		     geography + arts + math + science + physEduc;
	 average = total / 9;

	 // Display the total and the average
	 this.txtTotal.Text = total.ToString("F");
	 this.txtAverage.Text = average.ToString("F");
}

Return to the form.
Double-click the Close button and implement its event as follows:
private void btnClose_Click(object sender, System.EventArgs e) { Close(); }
Execute the application to test it
Right-click the form and click View Code

In the top section of the file, add the using System. IO; line

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.IO;

namespace ROSH1
{

Display the form
In the Toolbox, click the SaveFileDialog button and click the form
In the Properties window, change the following properties
DefaultExt: ros
Filter: ROSH Students Grades (*.ros)|*.ros|All Files(*.*)|
Title: Save Student Grades As

On the form, double-click the Save button and implement its Click event as follows:

private void btnSave_Click(object sender, System.EventArgs e)
{			
	 FileStream   stmGrades = null;
	 BinaryWriter bnwGrades = null;

	 // The information will not be saved if there is no name for the student
	 if( this.txtStudentName.Text.Equals("") )
	 {
		 MessageBox.Show("The report cannot be saved without the name of the student");
		 this.txtStudentName.Focus();
		 return;
	 }
	 // The information will not be saved if there is no school year
	 if( this.txtSchoolYear1.Text.Equals("") )
	 {
		 MessageBox.Show("The report cannot be saved without the school year");
		 this.txtSchoolYear1.Focus();
		 return;
	 }
	 if( this.txtSchoolYear2.Text.Equals("") )
	 {
		 MessageBox.Show("The report cannot be saved without the school year");
		 this.txtSchoolYear2.Focus();
		 return;
	 }

	 string strFilename = this.txtStudentName.Text +
		 this.txtSchoolYear1.Text + this.txtSchoolYear2.Text;
	 this.saveFileDialog1.FileName = strFilename;
	 // Display the Save dialog box
	 // Find out if the user clicked OK or pressed Enter
	 if( this.saveFileDialog1.ShowDialog() == DialogResult.OK )
	 {
		 // If the used provided a name that already exists for an existing file
		 if( File.Exists(this.saveFileDialog1.FileName) )
		 {
			 // Find out if the user wants to replace the existing file
System.Windows.Forms.DialogResult answer = MessageBox.Show(string.Concat("The student report exists already.",
					                                                   "Do you want to replace it?"),
								   "Save Student Report",
								   MessageBoxButtons.YesNo);

			 // If the user wants to replace it
			 if( answer == DialogResult.Yes )
			 {
				 stmGrades = new FileStream(this.saveFileDialog1.FileName, FileMode.Create);
				 bnwGrades = new BinaryWriter(stmGrades);

				 // Then overwrite it
				 bnwGrades.Write(this.txtStudentName.Text);
				 bnwGrades.Write(this.txtSchoolYear1.Text);
				 bnwGrades.Write(this.txtSchoolYear2.Text);
				 bnwGrades.Write(decimal.Parse(this.txtEnglish.Text));
				 bnwGrades.Write(decimal.Parse(this.txtHistory.Text));
				 bnwGrades.Write(decimal.Parse(this.txtEconomics.Text));
				 bnwGrades.Write(decimal.Parse(this.txt2ndLanguage.Text));
				 bnwGrades.Write(decimal.Parse(this.txtGeography.Text));
				 bnwGrades.Write(decimal.Parse(this.txtArts.Text));
				 bnwGrades.Write(decimal.Parse(this.txtMath.Text));
				 bnwGrades.Write(decimal.Parse(this.txtScience.Text));
				 bnwGrades.Write(decimal.Parse(this.txtPhysEduc.Text));

				bnwGrades.Close();
				stmGrades.Close();
			}
		}
		else
		{	
			stmGrades = new FileStream(this.saveFileDialog1.FileName, FileMode.Create);
			bnwGrades = new BinaryWriter(stmGrades);
						
			bnwGrades.Write(this.txtStudentName.Text);
			bnwGrades.Write(this.txtSchoolYear1.Text);
			bnwGrades.Write(this.txtSchoolYear2.Text);
			bnwGrades.Write(decimal.Parse(this.txtEnglish.Text));
			bnwGrades.Write(decimal.Parse(this.txtHistory.Text));
			bnwGrades.Write(decimal.Parse(this.txtEconomics.Text));
			bnwGrades.Write(decimal.Parse(this.txt2ndLanguage.Text));
			bnwGrades.Write(decimal.Parse(this.txtGeography.Text));
			bnwGrades.Write(decimal.Parse(this.txtArts.Text));
			bnwGrades.Write(decimal.Parse(this.txtMath.Text));
			bnwGrades.Write(decimal.Parse(this.txtScience.Text));
			bnwGrades.Write(decimal.Parse(this.txtPhysEduc.Text));
					
			bnwGrades.Close();
			stmGrades.Close();
		}
	}
}

Execute the application and create a record:
Save the record and close the form
In the Toolbox, click the OpenFileDialog button and click the form
In the Properties window, change the following properties
DefaultExt: ros
Filter: ROSH Students Grades (*.ros)|*.ros|All Files(*.*)|
Title: Open Student Grades

On the form, double-click the Save button and implement its Click event as follows:

private void btnOpen_Click(object sender, System.EventArgs e)
{
	 // Display the Open dialog box
	 // Find out if the user selected a file and clicked OK
	 if( this.openFileDialog1.ShowDialog() == DialogResult.OK )
	 {
	 	FileStream   stmGrades = new FileStream(this.openFileDialog1.FileName, FileMode.Open);
		 BinaryReader bnrGrades = new BinaryReader(stmGrades);

		 if( File.Exists(this.openFileDialog1.FileName) )
		 {
			 // Retrieve the values from the file
			 this.txtStudentName.Text = bnrGrades.ReadString();
			 this.txtSchoolYear1.Text = bnrGrades.ReadString();
			 this.txtSchoolYear2.Text = bnrGrades.ReadString();
			 this.txtEnglish.Text     = bnrGrades.ReadDecimal().ToString("F");
			 this.txtHistory.Text     = bnrGrades.ReadDecimal().ToString("F");
			 this.txtEconomics.Text   = bnrGrades.ReadDecimal().ToString("F");
			 this.txt2ndLanguage.Text = bnrGrades.ReadDecimal().ToString("F");
			 this.txtGeography.Text   = bnrGrades.ReadDecimal().ToString("F");
			 this.txtArts.Text        = bnrGrades.ReadDecimal().ToString("F");
			 this.txtMath.Text        = bnrGrades.ReadDecimal().ToString("F");
			 this.txtScience.Text     = bnrGrades.ReadDecimal().ToString("F");
			 this.txtPhysEduc.Text    = bnrGrades.ReadDecimal().ToString("F");
			 
			 // Close the stream
			 bnrGrades.Close();
			 stmGrades.Close();

			 // Since we didn't save the results of the calculations,
			 // call the Calculate button to do it
			 this.btnCalculate_Click(sender, e);
		 }
	 }
}

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