C# NET String.Compare issue

Question

I am working on some homework for class, and decided to add some extra stuff, and wound up confusing myself a bit. I have tried various comparison methods, and none of them seem to work, but I don't understand why.

Basically when an order is added to the system, it creates an instance of the class 'OrderInfo', and adds it to an ArrayList. In my code, I am using a foreach() loop to find the class instance that matches which entry in the ListBox they clicked, but something is wrong.

private void ordersListBox_DoubleClick(object sender, EventArgs e)
{
    if (ordersListBox.SelectedItem != null)
    {
        foreach (OrderInfo i in ordersList)
        {
            if (String.Compare(i.GetClientName(), ordersListBox.ToString(), true) == 0)
            {
                MessageBox.Show(i.GetClientName());
                break;
            }
        }
    }
}

do you really mean ordersListBox.ToString()? By default, this will not return the text of the selected item. — Jimmy
– Jimmy, Commented Feb 13, 2011 at 21:28

Bala R · Accepted Answer · 2011-02-13 21:24:59Z

4

Instead of

 if (String.Compare(i.GetClientName(), ordersListBox.ToString(), true) == 0)

try

 if (String.Compare(i.GetClientName(), ordersListBox.SelectedValue.ToString(), true) == 0)

answered Feb 13, 2011 at 21:24

Bala R

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Comments

Amokrane Chentir · Accepted Answer · 2011-02-13 21:23:54Z

0

For String comparisons it is better to use the Equals() method.

private void ordersListBox_DoubleClick(object sender, EventArgs e)
{
    if (ordersListBox.SelectedItem != null)
    {
        foreach (OrderInfo i in ordersList)
        {
            if (i.GetClientName().Equals(ordersListBox.ToString()))
            {
                MessageBox.Show(i.GetClientName());
                break;
            }
        }
    }
}

answered Feb 13, 2011 at 21:23

Amokrane Chentir

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Comments

SLaks · Accepted Answer · 2011-02-13 21:24:02Z

0

String.Compare returns a number, not a boolean.
The number will be positive, negative, or zero, depending on the relative alphabetical ordering of the strings.

You should call String.Equals, and pass StringComparison.OrdinalIgnoreCase.

answered Feb 13, 2011 at 21:24

SLaks

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Comments

flq · Accepted Answer · 2011-02-13 21:28:36Z

0

I doubt you really want to compare the string representation of the ordersListBox to some sensible string.

The default implementation of ToString() of any object is to output the name of the type of the instance. The ordersListbox most likely is doing just that. You will want to consult the SelectedValue.

answered Feb 13, 2011 at 21:28

flq

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Comments

user1113039 · Accepted Answer · 2014-02-13 13:48:48Z

0

You can also try this one.

 if (String.Compare(i.GetClientName(), ordersListBox.SelectedValue.ToString(), StringComparison.InvariantCultureIgnoreCase) == 0)
        {
            MessageBox.Show(i.GetClientName());
            break;
        }

answered Feb 13, 2014 at 13:48

user1113039

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