How to interact with 2 combo boxes in c#.net 4.0 in blow case study

This is a bit rushed and so may not be quite right but try the following.

Notice that you'll need to make some variables into fields rather than local variables so they can accessed from the textBox1_Click eventhandler.

Also, it's only necessary to load the Hashtable once:

// these variables need to be fields rather than local variables

private string[] lines = null;

private Hashtable tab = null;

private string path = @"C:\SUBS\FileReadFormsAuto\FileReadFormsAuto\TVOP.txt";

private string key = null;

private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)

{

key = String.Empty; // now refers to field

try

{

if (tab == null) // if Hashtable not yet loaded

{

tab = new Hashtable(); // now refers to field

lines = File.ReadAllLines(path); // now refers to field

foreach (string line in lines)

{

if (line.Contains("="))

{

string[] items = line.Split('=');

tab.Add(items[0], int.Parse(items[1]));

}

if (tab.ContainsKey(comboBox2.SelectedItem.ToString()))

{

key = comboBox2.SelectedItem.ToString();

textBox1.Text = tab[key].ToString();

}

else

{

MessageBox.Show("Invalid Key or Command Entered....\nPlease Enter A Valid Command.");

}

catch (Exception Ex)

{

MessageBox.Show(Ex.Message);

}

private void button1_Click(object sender, EventArgs e)

{

if (String.IsNullOrEmpty(key) || lines == null) return;

int code;

if (!int.TryParse(textBox1.Text, out code))

{

MessageBox.Show("Invalid code entered ....\nPlease enter a valid code.");

textBox1.Focus();

}

string search = key + "=";

int index = -1;

for (int i = 0; i < lines.Length; i++)

{

if (lines[i].StartsWith(search))

{

index = i;

break;

}

if (index > -1 && Convert.ToInt32(tab[key]) != code)

{

lines[index] = search + code.ToString();

File.WriteAllLines(path, lines); // save to file

tab[key] = code; // save to Hashtable

MessageBox.Show("The revised code has been saved to the file.");

}

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
This is a bit rushed and so may not be quite right but try the following.

Notice that you'll need to make some variables into fields rather than local variables so they can accessed from the textBox1_Click eventhandler.

Also, it's only necessary to load the Hashtable once:

// these variables need to be fields rather than local variables
private string[] lines = null;
private Hashtable tab = null;
private string path = @"C:\SUBS\FileReadFormsAuto\FileReadFormsAuto\TVOP.txt";
private string key = null;

private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
{
key = String.Empty; // now refers to field

try
{
if (tab == null) // if Hashtable not yet loaded
{
tab = new Hashtable(); // now refers to field

lines = File.ReadAllLines(path); // now refers to field

foreach (string line in lines)
{
if (line.Contains("="))
{
string[] items = line.Split('=');
tab.Add(items[0], int.Parse(items[1]));
}
}
}

if (tab.ContainsKey(comboBox2.SelectedItem.ToString()))
{
key = comboBox2.SelectedItem.ToString();
textBox1.Text = tab[key].ToString();
}

else
{
MessageBox.Show("Invalid Key or Command Entered....\nPlease Enter A Valid Command.");
}
}

catch (Exception Ex)
{
MessageBox.Show(Ex.Message);
}
}

private void button1_Click(object sender, EventArgs e)
{
if (String.IsNullOrEmpty(key) || lines == null) return;

int code;

if (!int.TryParse(textBox1.Text, out code))
{
MessageBox.Show("Invalid code entered ....\nPlease enter a valid code.");
textBox1.Focus();
}

string search = key + "=";
int index = -1;

for (int i = 0; i < lines.Length; i++)
{
if (lines[i].StartsWith(search))
{
index = i;
break;
}
}

if (index > -1 && Convert.ToInt32(tab[key]) != code)
{
lines[index] = search + code.ToString();
File.WriteAllLines(path, lines); // save to file
tab[key] = code; // save to Hashtable
MessageBox.Show("The revised code has been saved to the file.");
}

}