Question

Using Visual Studio 2015, how would I code the following Uodate button event handler in c#?

then displayed in the student list box. Create an interface as follows The initial form for the application should appear as follows Student Scores Students dd New. Lpdate Delete Ext To update, delete or add student information create the following form Enter Student Information Name Student ID MdtemRna Cancel Note: the Control Box property is set to false

Answer 1

Update button Handler :

In order to code for update button event handler following method needs to be added :

1. Add update button event handler in the code behind class for Student Scores form(.cs) file

protected void UpdateButton_Click(object sender, EventArgs e)

{

string studentName = null;

string studentID = null;

string studentIDNrank = null;

string studentInfo = null;

string studentRank = null;

if(this.studentListbox.SelectedIndex < 0)

{

MessageBox.Show("Please Select a student.");

studentLisbox.selectedIndex = 0;

return;

}

else

{

studentInfo = studentListbox.SelectedItem.Text;

int len = studentInfo.length;

int index = studentInfo.IndexOf(" ") + 1;// put number of spaces used to display between name and ID

studentName = studentInfo.Substring(0,index);

studentIDNrank = studentInfo.Substring(index,len).Trim();

index = studentIDNrank.IndexOf(" ") + 1;

studentID = studentIDNrank.SubString(0,index);

studentRank = (studentIDNrank.SubString(index,len)).Trim();

studentInfoForm f = new enterStudentInfoForm(studentName, studentID, studentRank);

f.ShowDialog();

}

}

//Method to update the listbox with updated details

protected void ModifyList(string studentName, string studentID, string studentRank)

{

int index = studentLisbox.FindString(studentName);

if(index >= 0)

{

studentLisbox.RemoveAt(index);

}

studentLisbox.Add(new studentNew(studentName, studentID, studentRank);

}

//Method to save the list in student.txt file

protected void SaveStudents()

{

//include code to add comma delimited

string itemText = null;

System.Text.StringBuilder sb = new System.Text.StringBuilder();  

foreach (object item in studentLisbox.Items)  

{  

itemText = item.ToString().Replace(" ", ","); //code to add comma delimter

sb.Append(itemText.ToString());  

sb.Append("/n ");  

}  

using (StreamWriter sw = new StreamWriter("C:\\student.txt", true))

{

sw.WriteLine(sb);

}

}

// Add the below code lines to code behind file of Student Information form(.cs)

//Constructor to set the student attributes as textbox text

protected void enterStudentInfoForm(string studentName, string studentID, string studentRank)

{

this.enterStudentInfoForm.txtbox_Name.Text = studentName;

this.enterStudentInfoForm.txtbox_ID.Text = studentID;

this.enterStudentInfoForm.txtbox_Name.Enabled = false;

this.enterStudentInfoForm.txtbox_ID.Enabled = false;

this.enterStudentInfoForm.txtbox_Midterm.Focus();

selectedStudent student = new selectedStudent();

student.Name = studentName;

student.ID = studentID;

}

//Okay button click event handler that will validate the entries in text boxes and

// set to the student object attributes

protected void okButton_click(Object sender, EventArgs e)

{

string studentName = txtbox_Name.Text;

string studentID = txtbox_ID.Text;

int studentMiderm = Convert.ToInt32(txtbox_Midterm.Text.ToString());

int studentFinal = Convert.ToInt32(txtbox_final.Text.ToString());

string studentRank = CalcLtrGrade(studentMiderm , studentFinal);

if( (studentName != null && studentName !="") &&

(studentID != null && studentID !="") &&

(studentMiderm != null) &&

(studentFinal !=null) &&

(studentRank != null && studentRank !="")

)

{

this.student.Midterm = studentMiderm;

this.student.Final = studentFinal ;

this.student.Rank = studentRank ;

if(student.valid) //object validation

{

// Add this to student list

studentScoresForm.ModifyList(studentName ,studentID , studentMiderm ,studentFinal ,studentRank );

// Save the student list to student.txt file

studentScoresForm.SaveStudents();

}

}

}